Hi Flicker
Welcome to NeuroTalk.
If you have a formal diagnosis of coeliac disease (an auto-immune response to glutens), which is not always easy to diagnose, then for most people avoiding foods which do not contain them works well.
I am sorry to read about your woes - as far as I know they are usually not related to coeliac disease.
Based on
Testing for food reactions: the good, the bad, and the ugly. - PubMed - NCBI, I am dubious about mediator release tests. From it, there are some validated tests for food allergies but mediator release tests are not among them.
In it mediator release tests are described as only being present on "consumer sites" which means that money changes hands for a test which has not been shown to be useful in a treatment sense.
All the best.