I have a large male cichlid and something is very wrong with him. I've checked the pH and it is normal. His lips look like they are sunburned! They are redish/brownish, peeling, and appear swollen. He won't eat and is not swimming much. When he does, he is tilted (head is upward) at a 45-60degree angle. He keeps "laying" on the bottom of the tank, almost as if he is resting. What should I do? What is wrong with him??

He has also developed a large black mark on the side of his body just before his gills. My other fish (convict and plecco) are exhibiting no similiar symptoms.
My water temp felt warm so I have lowered it. Could this possibly have caused these symtoms? I'm heading out shortly to go buy a H20 thermometer.