Another thing that unfortunately happens to a lot of us is additional intolerances. Lots of folks have trouble with dairy and soy. Some of us have trouble with corn or nightshade vegetables. Then there are salicylates, oxylates, lectins, and other natural chemicals in foods.
But I would start simple. Make sure you aren't getting cross-contamination. Then, if you are still sick, try doing away with dairy. If you are STILL sick, do away with soy. After that, if you are still getting sick, an elimination diet sounds in order.
Read as much as you can here. Ask lots of questions. We will help you figure this out! (((HUGS)))