Check his nostrils also,one of my roosters had funny breathing and a discolored comb,after checking him over i found his nostrils where plugged from sticking his head into his fermented feed(he loves the stuff)after i cleaned the inside of nostrils with a Q-tip,comb immediately resumed normal color and breathing became regular.
If he sounds congested,try steaming him in a bathroom with shower turned on.
If he sounds congested,try steaming him in a bathroom with shower turned on.