I'm sorry you didn't get any answers, chico.
When your kitties go out in the yard, do they ever drink from puddles or even a bird bath? I know it's not happening now cuz it's frozen out there, but I wonder if Rocky could have picked up something like giardia from water in the yard? It's not something necessarily obvious--I think there's a special test for it--but it
can cause diarrhea.
I hope the new vet can figure
something out--not only for your peace of mind but to preserve your pocketbook.
hazel can relate to big vet bills 