Bombur has EC, and it can take a bit sometimes before the Panacur can really take full affect. Bombur has been on back to back rounds of EC meds a few different times to resolve symptoms. Sometimes that’s just the way the cookie crumbles. Bombur has recurring flare-ups when he’s under stress from things like moving, or a bad molt. Bombur doesn’t have the neurological symptoms like your bun has, but EC and Panacur are definitely things you need to be patient with. Unlike an antibiotic where you see progress in a day or two on medicine, Panacur progress is usually around the 2 weeks mark. As I said, if there’s not a ton of improvement the vet will usually do a back-to-back course to get things under control.
EC is a paraiste, as Az mentioned, so it may come back again, or he may never get another flare-up in his life. The important thing is that it doesn’t mean he’s unwell or unhealthy, or doomed to death. No one would ever guess Bombur has EC by the way he runs around like a maniac for food, or hops on the couch for pets, or all the naughty things he does. It’s just a hiccup in his life, and your bun’s life too. The head tilt may take some time to go away, but he can still lead a productive and happy life with it.