Well, there are only 2 things I can think of. Firstly, due to covid I had been working at home from March to May. Before covid I would still go out a lot to cafes/social workspaces and get sunlight. And around mid-march I started running. By May I was running about 5k-7k daily throughout my neighborhood.
So we initially thought it was a bug related thing, but everything came back clean. We tried eliminating food, but nothing really seemed to have an effect after a week or two.
I spoke to my immunologist and he believes it's not food related as I already have food related allergies (peanuts), so eating something else should give me quick reactions like peanuts do. Also, he said it's rare for adults to spontaneously develop something like that. Bloodwork has been inconclusive because my IgE is so high that it's causing false positives. I did a diff of my allergy bloodwork from and back in October, and multiple values did increase.
I have tried basically everything- getting more sunlight, using sensitive detergent (3 different brands), cutting out coffee/gluten etc. Hell, we even replaced the carpet in my parents house with hardwood, and once I moved into my house we cut out the carpet as well.