It might go or it might not. The issue with not diagnosing and treating is that chronic diarrhea predisposes a cat to developing IBD. So by not getting rid of it you may end up with a lifelong issue.
I don't know what a PFC is, but I don't think you need to go to Europe any longer for the ronidazole...sounds like the vet might be a bit behind the times. http://www.wedgewoodpetrx.com/items/ronidazole-capsule.html
Any side effects cease if you stop the drug so although it is concerning with careful monitoring the cat should be fine. Sounds to me like they don't have any experience with testing and treating, and don't want to so have tried to put you off from pursuing it.
I don't know what a PFC is, but I don't think you need to go to Europe any longer for the ronidazole...sounds like the vet might be a bit behind the times. http://www.wedgewoodpetrx.com/items/ronidazole-capsule.html
Any side effects cease if you stop the drug so although it is concerning with careful monitoring the cat should be fine. Sounds to me like they don't have any experience with testing and treating, and don't want to so have tried to put you off from pursuing it.