I had bought a juvenile Soft Shell Turtle about a year ago. He has been doing great until yesterday I thought he was dying. It was like he lost control of his muscles, his neck was flopping around and just was not moving at all. I put him in his basking area, came back later and he's swimming and perfectly fine. He ate last night but then again when I went to turn his lights off and he was out of it again. I raised the temperature in the water and did a water change, maybe that will help but he is just floating today. His back end is straight in the air, he tries to swim to the bottom but floats right back up. There is nothing on his shell at all, by looking at him he looks perfectly healthy. Any ideas what it could be?