I agree with others who have suggested you run a PCR for tritrich. You can run the entire diarrhea PCR but I think you can also just request the tritrich alone which is much less expensive.
If you find that tritrich is NOT the culprit then I think you should consider investigating IBD or IBS. I have a cat that was sent back to me because of IBD that is also incontinent of diarrhea. I ran a diarrhea PCR just to make sure and he tested negative. I am now aggressively treating him for IBD and he is feeling better, and although his stools are still loose he is rarely incontinent.
If you find that tritrich is NOT the culprit then I think you should consider investigating IBD or IBS. I have a cat that was sent back to me because of IBD that is also incontinent of diarrhea. I ran a diarrhea PCR just to make sure and he tested negative. I am now aggressively treating him for IBD and he is feeling better, and although his stools are still loose he is rarely incontinent.