You are probably being bombarded with suggestions, and am overwhelmed, so it's probably not very useful to add yet another one, but .... Reducing carbohydrates

You are probably being bombarded with suggestions, and am overwhelmed, so it's probably not very useful to add yet another one, but .... Reducing carbohydrates significantly (as happens in keto and even paleo diets) anecdotally seems to make autoimmune disease and allergy quiet down significantly. I am not aware of any studies confirming this, but the anecdotal evidence in /r/keto and people I know seem to be overwhelming. It's also "cheap" to try in money terms (although the commitment and change are sometimes emotionally expensive). If you go keto, be sure to read about changes to electrolyte needs and how to avoid feeling bad (short story: you need more salt in your diet in the first few days of keto, or you'll get something called "keto flu").