My coop is in my barn which means it is quite drafty. With temps dipping below zero I put a heat lamp out and I have one (of 4) cockerels with frostbite on his comb. I agree that is what it looks like on yours, but yours is thankfully mild. Folks on here will tell you not to touch it as it may cause more damage. You can spray Vetricyn or something similar on it though. It is hard because you think you're doing something to help keep them safe but it does the opposite. Best of luck!!