I did get a pretty extensive allergy & asthma test recently which showed nothing wrong, would something like that show any results? I also went to an allergist years ago, he said I had an intolerance for biogenic amines, but then told me to cut out a bunch of foods that definitely aren't triggers for me. I had a bad bout of IBS at the time and there were things that clearly made it worse, but I think it was mostly stress-related, I was in an unhappy relationship and once that ended, so did the IBS. My main symptoms now are near-constant post-nasal drip that I've had since I was 18 (for which the only possible correlating factors I've found were starting birth control, but I've since switched birth control and it's made no difference what so ever, and moving to the town where I still live now), and constant relatively minor inflammation issues, like I've had a bunch of tonsil infections the past few years, some bouts of food poisoning that wouldn't go away on their own, and cold sores that got so bad I'm now on permanent meds because I kept getting eye infections etc.

But yeah, I'm keeping it on my radar just because everything else has been ruled out by now, I think. They've checked my immunology as well and found nothing odd.