Hello,
This is Dr.Christian. Welcome to JustAnswer. Since you are currently offline, I will answer your question as best I can but if you need more clarification or have more questions I should be online off and on through the day. It sounds like your rabbit has suffered a severe back injury. It is unfortunately very common in rabbits and causes paralysis of the rear legs, anus and everything behind the injury. He may even be developing a prolapse of the rectum due to the lack of nerve function to the area. There are infections that can affect the spinal cord and cause this as well. Unfortunately, there is not much to be done and he is certainly suffering. I would encourage you, if at all possible to call around to local vets and tell them your situation. I suspect you can find someone that could put him to sleep for a low cost or in some cases for free. You even have the option of your local humane society. Otherwise he will continue to suffer over the next few days.
Veterinarian
12 years of veterinary experience in medicine, surgery and behavior with exotics,canines and felines