The gasping for air may be caused by lack of oygen being admitted into the tank. Make sure you have a good air system going into the tank. the blotches sounds like a fungus. The best thing you can do is go to your local pet store and look at the antibiotics they have. On every package it tells the symptoms that it will treat.. look over your fish good before you go an find the one that looks like it fits his symptoms the best.
Good Luck!