Make a few calls and find a vet that will see your bunny. It is strange how few sill these days, but they are out there. There are so many different things that could be affecting your bunny, you really ned a vet to narrow it down for you. Sounds to me like and inner ear infection, but what caused it will determine which antibiotics you should use!
Try asking your current vet who would se a rabbit, they should know!
Good Luck!