Gastro-intestinal problems are hard to endure. Don't be afraid to ask to be referred to a specialist, or otherwise seek a second opinion, if possible. At the very least, tell your relevant MD "Hey, whatever you're doing is not working well enough. I need you to step things up, please." Doctors get inundated with various health crises every day, and can lose sight of variances after they've made an initial diagnosis. A good doctor will actually be glad that you've said something if a treatment isn't working as planned. Best to you and yours!