Kitten with Head Tilt

I have an apx 5 month old kitten. About a month and half ago, I found him unable to move. Vet did not know what was wrong but gave me Amoxicillin to give to the kitten (I had the same thing happen to another kitten apx a month before, that I wrote to you about, but the difference between that ones episode with the unknown illness and this ones is the other kitten had a very high fever and once the fever broke the ataxia and such disappeared. This kitten had no fever). The Amoxicillin apparently worked and within a day he was back up walking although slightly wobbly and with his head tilted to one side. I thought after he was through his round of antibiotics this head tilt would go away but it has persisted. The kitten has boundless energy now, runs and plays and tackles the others and shows no syptoms (symptoms) what so ever of being ill. I also thought perhaps his ear might be full of wax but when peering deep into his ear on the side that tilts, it is clean as a whistle. The only ideas I can come up with are inner ear damage or brain damage from whatever illness this was.
Do you have any ideas on the matter and also do you have any ideas of what kind of therapy I might give to him to help him overcome this head tilt?
One more thing, he does have a tad problem with balance as when I hold him and put him down suddenly, he sometimes rolls into the floor unable to plant himself firmly on the floor at first.
TYVM for any input into this matter!

[Dan Sims, DVM]

Idiopathic Vestibular Syndrome may explain the issue with the kitten as it usually affects young cats and will resolve on its own and it typically presents with no fever.
Sometimes the head tilt remains but the cat has a normal long life.