I am so sorry your Rabbit is so ill.
It sounds like your rabbit has Torticollis which is a disturbance to his vestibular system and affects his equilibrium. I printed this for you:
"In some cases, an ear infection appears highly resistant to the most commonly used antibiotics. A relatively recently "rediscovered" therapy that has proven highly effective in cases of head tilt, jaw abscesses and other infections of the head is treatment with bicillin, a rabbit-safe combination of injectible Penicillin-G Procaine and Benzathine. This has been used on rabbits who were deemed terminal and untreatable, and produced miraculous cures. It is something to consider if conventional antibiotic therapies are not effective.
While the antibiotics are doing their work, your vet might also prescribe other drugs to help restore balance and control the discomfort associated with vertigo. Meclizine (commercially known as Anti-Vert) is excellent for controlling dizziness, though it will not work for every rabbit. If meclizine does not control the nystagmus, your vet might prescribe a course of short-acting corticosteroids to reduce the inflammation interfering with the vestibular apparatus. We have found that these drugs can sometimes help restore normal posture even before the infection is fully cured.
It can sometimes take weeks or even months to completely cure an inner/middle ear infection. This may sound like a long time, but if supportive care is offered, and the rabbit continues to eat and drink normally and is still interested in life, it means she's not ready to give up. The condition is disorienting, but does not seem to be painful. The illness is temporary, if hard to watch, but it's worth a course of supportive care to see your bunny happy and running around again"
Here is the rest of the article:
And some others:
This can take a while to cure and other meds may have to be employed. Right now this bunny needs to be hydrated. You can get unflavored pedialyte in the baby dept of any store - it is for human children. Give him a few drops every fiteen minutes until he perks up. It is called Lectade in the UK and some countries.
Please get started ASAP and let me know how he is doing. I will be here all day.
I hope he will be better very soon.