I suffer principally with small intestinal bacteria overgrowth (SIBO) but this condition has caused large bowel dysbiosis with IBS symptoms too.
Some Fodmap's like Fructans are my enemy (presently) but it is now becoming apparent that I have developed some other food intolerances as a consequence of this condition which may or may not remain once the SIBO has gone.
Firstly I discovered the adverse effect of Sulphites which are used in preserving food. I follow a plant based diet and avoid most processed/junk food but non-organic versions of balsamic vinegar and the odd glass of wine caused bad flare ups. Organic versions generally don't include sulphites (South African organic wines do but it is normally expressed on the label).
There is little study evidence of the effect of sulphites and no clinical tests to determine intolerance, to my knowledge, but try excluding this additive and see if it helps. If you eat a lot of processed meats then beware, sulphites are used extensively.
I have also been suffering with occasional hypoglycaemia events, despite a healthy pancreas and usually normal blood glucose, or so it seemed. It now appears this is not due to an exocrine malfunction but a symptom of Histamine intolerance! I have avoided the precise history here as it has taken many tests and MRI's to reach this conclusion. But I have not had another Hypo' since cutting out tomatoes, spinach and other histamine rich or enzyme blocking (DAO)/promoting foods.
Again the research is thin on this subject but simply excluding related foods is an easy way to test for these intolerances.
Also consider Amines in general (histamine is one), Oxalates, Salicylates and Glutamates which maybe 'toxic' to you in general or while you are unwell. All it takes is some exclusion testing!
I have a list of these foods in pdf form complied by a reliable nutritionist. If any one wants a copy PM me with your email address. It is for info only, I am patient not a professional! 😊
Good luck!