How can I help my cat shake a bad cold?
I recommend going back to the vet. As others have said, respiratory infections are often viral. The viral infections sometimes accompanied by secondary bacterial infections. This might explain why the antibiotic helped but the symptoms returned. I have a cat that’s infected with FHV (feline herpes virus). She, too, has respiratory symptoms as a result of the virus. Not to worry if this is what your cat has, as it’s not contagious to humans and is very manageable with proper medication. It may be that this is what your cat has. If it is, putting him on an anti-viral medication can go a long way to keep the symptoms at bay. My FHV cat has been on an anti-viral (Viralys) for about 1.5 years and it makes a big difference in her symptoms. She only has flare ups occasionally, and the vet prescribed nose drops to use when she does have a flare up… they help quite a bit. Hope this helps… and best of luck and health to your kitty.