in case anybody has a similar problem, i found the issue with mine and it was really causing me to worry. it was tonsil stones. however, i could not see them when i looked at my tonsils. i bought a water pic and it took many times spraying the tonsils everyday until i broke somethign up and brownish gunk came out. i don't know exactly where it came from, somewhere in or around the tonsil. i still get them, but i know more about how to get rid of them. just knwoing its not a stomach issue put me more at ease. if anybody has a terrible rotten crap taste in mouth, especially when swallowing, and can't see any white tonsil stones when opening mouth, its possible that it is still your tonsils as it was with my case.
I would start a probiotic. Get Metamucil pills and take them with a glass of water. For my boyfriend, this stops him from getting heartburn, apparently from stopping splashing. Give it a try. It helps with digestion and cholesterol as well.