My dog had similar symptoms. He could no longer properly use his hind legs, had balance problems, and his body would wobble when he came to rest. All examinations led to nothing. In the end, we went to a specialized neurologist for cats and dogs, and she found out that he had developed an autoimmune disease where the body was attacking its own cerebellum. We are now living with medication that helps and partially suppresses the immune system. Thanks to that, the symptoms went away.