Wow, sorry to hear it hasn't gone away. Have you checked out diverticulitis? A co-worker just had that and it was very serious. Her symptoms at work were just major bloating and burping.
That sounds funny writing gas was her main complaints at work, so I need to explain. I don't want to scare you, but that night her pain got so bad she went to the hospital and they diagnosed her with diverticulitis that ruptured, and operated and saved her life! Apparently, it can cause sepsis, so I wouldn't take it lightly if that's what you have.