This was TJ when I first got him, and for the next year of his life. Those noises sounded like a monster in his belly. He would have this globby poop, mucus poop, diarrhea and eventually vomit too. His blood work came back normal, as well as all the fecal tests. His folate level were very high though. We tried a single source protein diet (duck/potato) and nothing else, although I think they made duck/potato treats too. And Metro, but he was still having the episodes. Then we moved onto Tylan Powder every day, and this was finally what stopped them (after about 6 to 8 months later though)
If you can find my past posts, TJs episodes are what brought me to find YT
