I think I have a very similar case to you. I used to be able to eat whatever I want then all of the sudden I can’t eat anything with out an absurd amount of gas build up. It’s just gas, and the gas causes so, so much pain that I’m vomiting up gas. To be specific, I don’t vomit but vomit gas. Then I develop weird flushing fast heart rate and quick breathing. Are these symptoms similar to yours ?