Have you tried homeostatic soil organisms/probiotics? Garden of Life is one brand, but it's been reformulated and many of the organisms were dropped. Swanson Vitamins has a HSO probiotics that has all of the ones that GOL used to have and it's way cheaper. I used Jordan's GOL Primal Defense back in 2003 for my ibs that was set off by a gall bladder attack.
I haven't used it in years, but it really helped me. I followed his protocol of taking 4 tablets 3 times a day.