A couple of days ago my golden retriever was hesitant to go up the stairs and when she got up, she went to jump on the bed and cried. now she wont go up the stairs at all. We have tried luring her with treats and only a couple times it has worked. She is normal with her other physical activity and other stairs she is fine going up. Also, we took her to the vet and they thought it was her back so we got pain killers. However, why would it be that when she can get in the car fine? Any suggestions on what it could be?