You've mentioned food elimination but have you had the 5 Day Extended Patch Test? If not Google this test. I've had the True Test Patch Test twice and learned of over a dozen contact allergens I need to eliminate for life. This is not a food test, or the simple 30 minute environmental patch test. It takes 5 full days with patches placed over the entire back torso for 5 days. It's expensive, over $1,500, but most medical plans and Medicare covers this test.
Like you I have dealt with several autoimmune issues. Eczema (3 different types) and Chronic Lymphocytic Leukemia, CLL. Since patch testing and following the yeast elimination plan, I will get to, all forms of eczema have been in remission for 5 years and my CLL disappeared without treatment over 15 years ago without explanation or any treatment or change of diet or contacts.
Many mentioned Candida. If you haven't already read The Yeast Connection Handbook, by Dr. Crook, MD do so. It's short and simple and can buy a used copy cheaply. I not only eliminated dozens of my positive contact allergens from either contacting me or off gassing into me but followed the Crook diet plan diligently. No more corticosteroid shots. No more sleep deprivation from the maddening itching always more noticeable and acute at night.
A note on off gassing of allergens, one of my allergens is to memory foam because of an element in rubber, Mercaptobenzothiazole, MBT, which is used to accelerate the blending of materials, like in elastics and memory foam. Memory foam off gasses this element. I had purchased a mattress containing memory foam about 6 months earlier. It had a dust mite cover and a heavy cotton mattress pad. Previously I had this internal and external itching for a few years, but it exploded after sleeping on this mattress for a few months. Thank goodness for this 5 Day Test or I would never have been able to identify part of the reason for my itching, burning and taser like stinging. That said, I also had to detox my body of yeast. Mind you, I did not have any classic female yeast symptoms. I had to kill off the yeast colonies residing in my colon, which we all have. These colonies create waste which passes though our intestinal linings and into our blood stream and raise our histamines. The Dr. Crook book explains, in layman's terms why this happens.