I use to have tonsil stone and they smelled so bad! I decided to have my tonsils removed and my breathe smells a lot better and my tongue is very pink. Before the surgery my tongue was white and I always had a bad taste in my mouth no matter what I ate but now I don't. I don't think the surgery have fixed my odor problem completely but it has helped a lot.
Try to use a tongue cleaner! Use it after each meal
Avoid dairy like the previous post mentioned.
I also started avoiding gluten and that helps a lot
And drink plenty of water!
Good luck!
Btw how did your dr appointment go with the GI dr?