Temp's at 86? That's a little high isn't it? Try lowering it to around 80 or 82. You'll have to do this over a period of a couple days though or else you'll stress him out and make him worse. I don't know if that could be causing his problem, but it seems like a good first step. If you don't have a thermometer you might want to get one. Heaters can say what they want, but may not be accurate. The floating thermometer is the best kind to go with and are only a couple bucks at Wal-Mart. How many days since the water change? Did you try to match the temp of the fresh water before the change? What's the water perameters? (ammonia, nitrite, nitrate) If he's having trouble getting to the surface, lower the water level so he doesn't have to struggle to breath. Is there any other symptoms? White poo, spots, etc....