He should have built up immunity to the cocci on your property, but if they are exposed to new strains through moving to new soil or exposure to a new chicken, they can still get it. Symptoms of lethargy, weakness, puffing up or hunching, and diarrhea or blood in poop can be signs. Corid or...
Pictures really help to show what you are seeing. White on combs sometimes means dry skin or can mean favus, a fungus that is treated with miconazole or other anti-fungal creams. Here is a thread about it: https://www.backyardchickens.com/t/154624/favus-on-rooster-comb-please-help
If you have any electrolytes to put in his water or something like Poultry Nutri-Drench, it may help him if he is dehydrated. When a chicken is lethargic I would think about fluids, possible cocci if you have added any new birds or he is new, mites, or worms. Open pans of water in the shade...