Please could you write further on Allergic Contact Dermatitis and the microbiome? I am convinced there is a clear connection there, and note one article you reference above specifically supporting the same also. Would be very interested in your holistic take on the same, as you have done with POTS and MCAS.
The gut microbiome alterations in allergic and inflammatory skin diseases – an update  “The gut microbiome alterations are linked to the pathogenesis of the allergic, cardiovascular, gastrointestinal, metabolic, neurodevelopmental, psychiatric and neurodegenerative diseases and cancer. Moreover, there is increasing evidence connecting the skin condition with the gastrointestinal microbiome, which has been described as the skin-gut axis.”
Bacterial Dysbiosis and Translocation in Psoriasis Vulgaris  ” Alterations in the gut microbiome have been characterized by a decrease in the Bacteroidetes phylum and an increase in the Faecalibacterium genus… The abundance of Faecalibacterium praunitzii was reduced to a greater extent in patients with both IBD and psoriasis, when compared to patients with only one of the conditions…IBD has been associated with psoriasis since the 1970s (Verbov, 1973; Yates et al., 1982; Lee et al., 1990). However, this association has largely been disregarded. [Also applies to UC and Crohn’s Disease]”
“Constipation was an associated factor for development of atopic dermatitis (AD) (1.17) and AR (1.17), regular intake of lactic acid bacteria was not an associated factor for development of allergic diseases but was a factor for remission of AD (1.22)” 
At first look, it looks like medical professionals dealing with Allergic Contact Dermatitis and similar conditions, do not want to deal with the gut microbiome. I call this the “It’s not in my wheelhouse” or “I want to keep into my thin silo” syndrome. There is a nasty situation created by excessive specialization of medicine and medical research.
I hate to say it, but the fastest way forward (and to get relief) may be doing citizen science via https://microbiomeprescription.com/ This depends on people with Allergic Contact Dermatitis getting appropriate 16s tests (see suitable providers here as well as which ones are most popular here). The site will automatically show relationships once we get 20 or more annotated samples uploaded.
I have added these to the symptom list on the site.
In writing another post, I discovered that I had not included this in my review of adaptogenic supplements. Adaptogenic means something that moderates the impact of stress. Stress is very common with ME/CFS and should not be ignored. The earlier posts were:
“The treatment group that was given the high-concentration full-spectrum Ashwagandha root extract exhibited a significant reduction (P<0.0001) in scores on all the stress-assessment scales on Day 60, relative to the placebo group. ” 
Probiotics can increase or decrease iron. Our knowledge is limited. If increasing iron is critical then avoid any probiotic containing L.acidophilus. Make sure that you are taking L. plantarum 299v and L. casei
There has been a flood of suggestions over the last year for COVID-19. In general, the suggestions are believers in some cure-all supplements, preaching their gospels. The more responsible one register trials and start (example).
The following are what has studies supporting some speculations.
” the estimated risk of developing respiratory failure was eight-fold lower in patients also receiving oral bacteriotherapy… (Sivomixx® a multi-strain product containing five strains of lactobacilli, two strains of bifidobacteria, and one strain of Streptococcus thermophilus) “
“The formulation administered in this study contained: Streptococcus thermophilus DSM 32345, L.acidophilus DSM 32241, L. helveticus DSM 32242, L. paracasei DSM 32243, L. plantarum DSM 32244, L. brevis DSM 27961, B. lactis DSM 32246, B. lactis DSM 32247. Ormendes SA, Lausanne, Switzerland which gifted the product Sivomixx® (SivoBiome® in USA)”
“a significant predictive power of the four variables: (a) low (<50 nmol/L) 25(OH) vitamin D levels, (b) current cigarette smoking, (c) elevated D-dimer levels (d) and the presence of comorbid diseases”
“Little evidence from observational studies and trials to date have evaluated the effect of high-dose cholecalciferol[Vitamin D] in hospitalized COVID-19 patients.” i.e.
“Results from this retrospective analysis demonstrate that two consecutive doses of 200,000 IU cholecalciferol (total of 400,000 IU) can significantly improve the outcome in patients affected by COVID-19 that are also burdened with three or more comorbid diseases. “
“SARS-CoV-2 patients with acute respiratory distress syndrome show elevated fibrinogen activity, high D-dimer levels and maximum amplitude of clot strength. Platelet count, fibrinogen, and standard coagulation tests do not indicate a disseminated intravascular coagulation. ” 
“the fibrinogen values in patients were higher than the control group (p < 0.05). ” 
Piracetam (where available) may lower fibrinogen levels
A reader asked me about this and I have not had to deal with it but I know it is common. Acid Reflux is also called gastroesophageal reflux disease (GERD). So I am doing a summary of my gold standard sources (a.k.a. PubMed). Internet legends are abundant; I know from prior posts that often they got established from some early study that did not replicate, or was even misread… and the legend just kept going on and on by being repeated. You may also wish to review my 2016 post on this topic
“. After diagnosis, the most common off-label, first-line treatments were:
For US women  “The five factors include normal weight, never smoking, moderate-to-vigorous physical activity for at least 30 minutes daily, restricting coffee, tea and sodas to two cups daily, and a “prudent” diet”
“GERD is common throughout the world, and its epidemiology is linked to the Western lifestyle, obesity, and the demise of Helicobacter pylori.” 
” The represented logistic regression shows that family history of GERD, marital status (divorce), smoking, physical activity frequency, tomatoes/tomato-based foods, salty foods, acidic drinks, frequent use of analgesics, and nonsteroidal anti-inflammatory drugs (NSAIDs) consumption shows statistical significance and association (P < 0.05) with increased risk of symptomatic GERD.” 
GERD takes NSAIDs more than controls
GERD eats chocolate less than controls
GERD eats Tomatoes/Tomato-based food more than controls
GERD drinks more citric drinks than controls
GERD drinks more tea than controls
GERD drinks less pop than controls
GERD smokes more than controls (note: smoking is often associated to stress)
“Most gastrointestinal benefits of probiotics have targeted the lower digestive tract, and limited data regarding the upper digestive tract have been reported, particularly for GERD….The aim of this systematic review was to examine the efficacy of probiotics in alleviating the symptoms, incidence, and severity of GERD in the general adult population, as this has not been done before.” 
compared with the placebo, postprandial distress syndrome scores declined significantly with the L. gasseri LG21 intervention (37.5% vs. 17.8%)….the underlying mechanisms of L. gasseri LG21 for improving FD-associated reflux are linked to postprandial effects, involving improved protein indigestion and increased gastric emptying.
Hydrochloric acid (HCL)/betaine/pepsin
This is often suggested on blogging and personal opinion sites. I was unable to find any study supporting it’s use and some studies indicating that with some sub-types, it may make it worst.
“Decreased acid sensitivity in individuals with increasing body mass index may play a pathological role in symptomatic modulation of patients with GERD.” 
“This study shows that a carbohydrate-free diet and/or highly hypoglycidal diet that is enriched with acid pH foods appears to lead to a decrease in the pH of the gastric contents, thus inhibiting the further production of hydrochloric acid with a reduction or disappearance of heartburn symptoms that are typical of gastroesophageal diseases.”  So less HCL results in an improvement.
Herbs / Bitters / Herbal Tonics
While effectiveness is cited in two studies, only a kampo herbal medicine is explicitly named. It may be worth while to try different traditional digestive bitters (as opposed recently created ones)
“The multiple mechanisms of action of medicinal plants[Ceratonia siliqua and rikkunshito] in GERD other than anti-secretory properties appear to provide more efficient treatment and helped to manage the histopathological changes associated with this disorder”
“Although their active components or the mechanism of action were not known by the ancient Persians at that time, their persistent use during different centuries might indicate their effectiveness. Owing to their potential, medicinal herbs are a viable option for the treatment of diseases like GERD even today.”
As stated above GERD tend to be a western diet disease (and that has been proposed also for the incidence of autism). In terms of life style, the following suggestions should be considered (all of these items appear to be associated to why GERD developed):
No evening snacks
Decrease fat and meat content in the diet
No soft drinks, citric drinks or tomato based diet (sorry Pizza lovers!)
Increase chocolate – ideally 70% cacao or more
Daily exercise for 30 minutes
No coffee or tea with caffeine
Work on sleep — melatonin may help with this, and also the microbiome
Lactobacillus gasseri probiotics
REDUCE STRESS in your life — yes, it CAN be done. Stress is a state of mind (move on!).
Thus the whys…
Not having your digestive tract EMPTY by bedtime (think of circadian rhythm for digestive system being off)
High fat and meat content in the diet (takes longer to digest — see above)
Soft drinks, caffeine(tea, coffee) citric drinks or tomato based diet (sorry Pizza lovers!) – alters bacteria
A lack of exercise (impacts microbiome)
Stress (impacts microbiome)
Not having a good breakfast (think of circadian rhythm for digestive system being off)
On a bit of a speculative nature, given that the mouth microbiome may be a significant player, altering it may be beneficial. There are three items that I would look at:
Symbioflor® 1 – for illness of the respiratory system, and is likely to also alter the oral microbiome
Two probiotics from Japan that comes as hard tablets suitable for sucking/slowly dissolving in the mouth
I have seen several children (and the literature agrees) with (very) high Bifidobacterium level, typically without an identified species. We not that there are both increases and decreases in Bifidobacteriaceae shown below. PPI should be use with caution.