Does anyone have a recommendation for tests to check for these? if you are searching, the word "allergy" is usually reserved for life threatening instances of the condition. the words, "intolerance" or "sensitivity" are usually used for conditions that are discomforts, i.e. digestive, rashes, red eyes, itchy skin etc.

WRT allergies: Consider plants; things you are drinking; washing powders (although more relevant for skin irritations); pets (more relevant for respirator problems).

As your problem is digestive it's probably safe to look at things you are consuming.

I would suggest eliminating things; or running self-tests. i.e. eat nothing for a few hours then eat a slice of bread - if you are fine to eat that you are probably not sensitive to wheat.

This can either be done by writing out your full diet and testing each part, or by testing the top 8 as mentioned above.