You need to get your cat to the vet!!!! There could be something very serious going on here. Depending on how long the condition has been going on, it could mean the difference of getting healthy again, or not.
Even broken bones don't reset themselves, and if not taken care of in time, it could grow back together in the wrong way, and permanently cause pain for your cat, in turn, the cat would never be very healthy again, and would die sooner rather than later. Hope this helps, good luck, get the cat to the vet please.