Maybe you've had bad experiences with doctors, but that has not been the case for me. I've had many tests done, but you can't just go in and ask them to do tests on your entire body. First, it probably wouldn't be covered by insurance, and second, they are also treating based on symptoms. I understand that the GI tract runs from your mouth to your butt, so it could be an issue there. They have suggested I go to a GI specialist.
The first biopsy I had a long time ago showed hyperplasia, exocytosis, hyperkeratosis, actute and chronic inflammation.
Second biopsy I had, which was a punch biopsy showed hyperkeratosis, acanthosis and focal spongiosis
The only thing slightly high with my blood tests was Iga(s) - it was 391 and their range was 61-356.
Recent bacterial swab showed Serratia, but this was more than likely a development after I had the laser surgery. That is currently being treated.