I was reading a book about food intolerance and he does go into the case of a woman who had 'tried everything' and still wasn't well but when she went to see a psychiatrist he was able to bring up deep psychological problems that she had never related to her physical symptoms. Within months she was better.
This may be an avenue you have already tried. If so, apologies, but you don't mention it in your post so I thought I would raise it.
best wishes for the future. stephen