Gus and Lucy were playing in the backyard all day yesterday and I locked them up for the night and everyone was fine. I went to let them out this morning and found Gus cant even stand up! He sits with his back leg stretched all the way out and he tries to stand but all he does is flop around. What do you think happened to him? He was perfectly fine last night and all of the sudden he cant even stand let alone walk...Any help would be greatly appreciated! I just don't want to lose him.