Cure Gastrointestinal Disorders

Rotten egg smelling farts/burps/stomach pain/cramping followed by diarrhea/vomiting. I am at a loss and do not have any remedies for this, doctors are no help and diets and nutrition do not seem to work, this has been an ongoing issue for years and I know I am not alone however the only thing I've heard of is Magnesium supplements but this does nothing for me I'm just looking for someone to help. My gallbladder was removed one month ago and I believed this to be the culprit but now the problem is back again and I've had scans and tests done and they found nothing to be wrong this is not in my head and I'm looking for an alternative to the doctors who seem to know nothing pls help me find some answers I don't know where else to turn.