I agree that the only thing that will help this guy is vet treatment. It could be an ear infection or a very bad case of ear mites, based on your description. Both are incredibly painful and can only be treated by prescription meds. The fact that he's leaning means that the organ in his ears that tells him which way is up and which way is down (vestibular organ) is affected, and that can make the bunny very nauseous as well.
Other options to pay for treatment are Care Credit, a vet credit card, and IMOM, which is a charity that helps people whose pets need vet care they can't afford. I think it's IMOM.org.
If you cannot afford treatment, please consider surrendering the animal to a shelter where he can get some vet care. He's in a lot of discomfort and deserves to have this treated or to not suffer anymore.
If you are experienced in medicine (ie you know how to give sub-cutaneous injections), there are some other options you can try on your own as a last resort, ideally the last resort before surrendering the animal.
I hope this does not sound harsh, but I don't want him to suffer. I hope one of the other options, like a vet payment plan, Care Credit, IMOM, or even a local rabbit rescue can help so you don't have to surrender him.
Another resource is Save A Bunny, they're in San Fransisco area, but they're very passionate about helping sick bunnies and may have funds and/or another rescue contact to help you.
http://www.saveabunny.com/
