From looking at the symptoms you have posted, it seems to me that you have the same thing that I had for many years while I was at University. I traveled overseas in that time and came back and I still had it!
I went to many doctors etc. None could find anything wrong with me. I had pills, special diets etc. It's just 'theory of the week' for doctors, believe me. You do have real physical symtoms, you know that.
Hopefully you will come back onto this forum so that I can establish if you do have the same thing, and if so the steps that you can take to recovery.