You can still care for him, it's just more work and learning how to care for him the right way. I bought a book online called "When your rabbit needs special care".
I would say the number one thing is keeping him clean. If he has any urine or fecal matter on his body, you have to clean him up. The urine can burn his skin and the feces will attract flies. One of my boys got Fly Strike which can be fatal for bunnies. I think he had dirty fur and the flies smelled that and laid eggs on him which hatched into maggots which start eating into his skin. Plus he has such limited mobility that he couldn't get away.
Like I said, I am treating my boys with Safeguard just in case it's E Cuniculi, and I am hoping it works, but I am not too hopeful for Big Brown. Bobby may come out of it, but Big Brown is pretty much disabled, probably permanently.