I think Covid triggers food sensitivities. Since having Covid I have developed non celiac gluten sensitivity. I cannot eat ANY wheat/gluten. If I do it feels like someone has poured cement into my intestines that has hardened in to concrete. The constipation was horrible. I finaaly found a great functional medicine doc. She had me start taking 1000mg of magnesium/day. The relief was almost instant, and I have finally had great 4 months and counting. My functional doc also ordered an array of various CYREX tests. The one that has really changed my life is the dairy reactivity test. My butyrophilin reaction was 4x the high end of the normal range. I have been taking thyroid med for the past 25 years , just to stay in the higher end of the normal range. My doc advised me to cut out all the dairy for 6 weeks. I did that, and my GI issues improved even more. In addition to that, my doc ordered the Labcorp advanced thyroid profile. After being of of dairy for 6 weeks, my thyroid is now operating exactly in the middle of the thyroid health range. It has always been in the 4.6 range. It is now about 1.4. It has never been this perfect. In addition I have more energy than I have had in 30 years. I am 71 yr. old. I do not know what triggered the butyrophilin reponse> All I know is NO MORE DAIRY For me. The other interesting thing is that a high reaction to the butyrophilin in milk can also indicate M.S. Many M.S. patients go into remission by stopping all dairy. 85% of the caucasian population has some level of reaction to butyrophilin. This was proven is Europe by doing a random sample and test of the public blood bank supply. It seems that the trigger has been the Holstein milk that is so widely used through out Europe and the U.S. Holstein milk is the highest in milk fat of any dairy cow. Butyrophilin resides in the fat membrane of the milk fat molecule. There is also numerous other disease links including autism in children that is suspected to be triggered by butyrophilin.