I was cleaning my tank and notice that my small frog was laying upside down on th ebottom of the tank. He usually doesn't like my hands too much but today he actually let me hold him. He keeps turning over onto his back. It's like he can't stay upright. He just laid in my hand at the top of the tank. I was trying to help him stay up to breathe. He seems to be having trouble swimming. I don't know what to do. He doesn't have any signs of illness other than what I mentioned. Please help!