I can relate. After decades of an increasing problem, I saw a Gastroenterologist who determined that there was an imbalance of the chemistry in my colon. He prescribed Colestipol and after a dose adjustment I have not had diarrhea unless I ate something that I know sets me off. I was recently taken off the Colestipol by another physician during treatment of another disorder and the problem has not recurred.
My suggestion is to see a gastroenterologist and avoid wheat as much as possible.