Food allergies are hard to test for sometimes, unlike testing for allergies to other things like pollens. There are also sensitivities that can create just as much trouble, which are not true allergies. Your body might not always react exactly the same each time you are exposed to it. Sometimes lots, and long lasting ( weeks ) sometimes very subtle, sometimes you don't notice. We hear food allergy and think rash, or tummy problems, this is def not always the case.
When your T mentioned Fibro, why did she mention it? Can you think of any other symptoms, small, large, anything at all? I think you should talk to a physician about this instead of your T, or both. But a T cannot do much, actually nothing to rule out anything physical.
If I told you the symptoms I have been dealing with for my whole life, you would be shocked that even tho I had been seeing dr's my whole life, only recently have they found the causes.
I hope you see a dr about this stuff, just to be safe, and because you need help with whatever is causing this.
I know you are very dedicated about the management of your MI, so while it is not fun ..yup I know, the management of your physical health is just as important.
Also you have an Ed similar to me. Long term? That could have a place in this as well.