I have a green tree frog that I have had for a few years now and he has started acting very strange. I think he has somehow injured himself. When he moves, his head wobbles back and forth like he has broken his neck or back. He still hunts but is not very good at it. The only crickets he can catch are the ones that have lost their legs. Here is a video that shows what I am talking about.

Frog, Beane - YouTube