You really need to post a picture, or a better description. There are a couple of things it could be. What does the black stuff look like? Are they large, small, scabby looking, or do they look like BB sized specks?? Does it cover the entire comb, or is it spotty?? Have you tried to rub it off? ...stanNeed help
What is this black stuff on my chickens comb. Was on one hen yesterday now on two today not sure if it was from the four roosters in there picking on her so I put them out.