One of my new frogs, Esteban, hasn't been eating and has been rather lethargic. It wasn't until tonight that I noticed his back leg is hurt. Where it's white (on the kneecap) it doesn't bend, so he can't swim. I feel so bad because he's probably in a lot of pain and I don't know what I can do if anything. Please please help. I also just looked at a video I took yesterday and he was swimming fine and his leg looked fine. What could've happened???