About the possible bone damage... I would think that if they had been damaged enough to cause this problem, it would have been apparent immediately, or at least almost immediately. Sort of like people don't walk around on a broken leg for years and then suddenly develop a limp. I'm just guessing. I'm glad to hear you have already spoken to your vet and are taking them to see him. I hope he can help.
Sorry. When I posted about it, I should have said I saw the notation on the photo that it was not yours. I would appreciate a PM about it, thanks.