I have a 7-year-old AFT in my classroom as a class pet. I have had him since he was a baby. He has done very well over the past 7 years, eats well, is active, and not fazed by the 3rd graders in my room. About a week ago, I noticed he seemed very thin, his backbone is showing, his fat tail is very thin, his upper jaw has receded inward, and his right eye does not open. He isn't very active and when I fed him the usual 10 crickets, he didn't, or couldn't, move toward them to eat them. He has been drinking a lot of water too. I have moved him away from the noisy classroom to see if that helps him. I can't seem to find out what's wrong with him. Does anybody have any ideas?