My guppy who's a males seems to be getting worse every day, and I think he's in pain. I noticed he had a hump on his back and I thought it was nothing at first and then a month later I couldn't find him in my 4 gallon tank. I finally found him under a rock but he couldn't swim up. I moved him out of that tank and into a nursery tank. He seemed to be fine for a day or two and today I woke up and noticed that the hump on his back is getting bigger and it looked like it was weighing him down. I think he's in pain and I want to help him. Any suggestions?