I can soooo relate. I had constipation, digestive problems, bloating and gas for years. It makes you feel horrible (not to mention looking pregnant). I still have ocassional times when it bothers me a little, but it doesn't usually last long – and I normally find that the reason is, I've forgotten to take my probiotics for a couple of days.
Another thing that has helped me with digestive problems is acupuncture. Don't know if you've ever considered that, but I've been pleasantly surprised at the number of things it helps.
Have you ever tried Activia? I haven't but since eating yogurt has helped me with some stomach upsets in the past, I've thought about it.
Again, I hope your problem clears up very soon.