My cat is having exceptionally loud bowel sounds.?

He is 8, neutered male, sweet as sugar. He's been acting a little "off" for about 6 weeks, but nothing I could really point at and say he is sick. But now it is all adding up. He has vomited a dark liquidy stuff twice this week and a hard, kind of fudgey one once. His tummy is moaning and groaning, sometimes very loudly. After a loud one last night, we both jumped, and then he let out a long, low moaning cry. (He is a talky cat, but this is a new sound heard lately.) He also passed a bit of gas twice that i smelled. He seems uncomfortable in positions that he usually lays. He is eating a little bit, but often. He is a dry Iams guy, and I am surprised that he is consenting to eat a little baby food chicken today (about a teaspoon full twice),he seems to be drinking enough. Not playing, just wants to be held but not petted. There are 4 cats using our huge litterbox, so i cant identify Myrrhy's stools... no diarrhea in there, but was one really *long* one.

I've moved and have no vet. Trying to get a reference all day...and now it looks like no vet til monday.

Any help or suggestions thankfully received. Ive had cats for 40 years and never had one with bowel sounds i could hear so far away.