Hi, I Have Episodes Were I Have Gas Build Up

Hi,
I have episodes were I have gas build up in my stomach, with some stomach hurting a knowing pain then I begin to belch. It slowly moves to my intestines and they sound like a boiling pot of water. I can hear it then I start to pass gas and then have diarrehia and sooner or later make myself vomit to get what is ever in my stomach out. When I belch and also pass gas the smell is too horrible to even describe, it can run a person out of the room including myself. I have tried many times to get this across to my Dr. but have no luck. It feels like something has not digested so I make myself vomit to get it out. Once I do I am not hurting in my stomach any more or sick to my stomach any more. But till it passes through I still will have diarrehia. Any ideas? I am starting an episode now, I can tell when it is coming on.