I have had my spotted salamander for about 2 months now and I just noticed that one of his back legs in injured. He does not use it often and it seems to just drag and there is discoloration around where the leg meets the joint. This is the first time I have noticed any issues and I try to check him every few weeks. I have a mixture of forest floor and organic soil substrate and I have been feeding him crickets and earth worms. I have noticed that he has been in his water bowl a lot more lately. What should I do?