My goldfish is having trouble swimming. He seems tired. He doesn't want to move much and he sinks to the bottom. If he doesn't lean up against the glass, he rolls onto his side. Something about him looks weird. I can't put my finger on it. I guess he looks a little swollen and his eyes seem to not move together, kind of like a chameleon. I don't want to lose him. Please help. What can I do?