If you think it's frostbite..and it has been that cold out. Vasoline is great on their combs...insulates them
First you can put a heat lamp in the coop. (secure so you don't start a fire) And then for the comb, the best you can do is to put a little neosporin on the comb every day. The comb won't grow back, but the black will eventually fall off.
Welcome to BYC If the weather gets below freezing, the birds are at risk of frostbite. Be sure the coop isn't holding humidity and is well ventilated if possible. As the poster above stated, You may want to hang heat lamps in the coop making it above freezing in there - but not by much. Put neosporin on the comb and wattle daily, the black tips should fall off. If it gets infected, which IS a possibility, you will have to get a sharp pair of scissors and trim off the black on the comb and/or wattle. Frostbite is dangerous. It not only can set up infection - which can kill, but may also cause fertility problems. To protect the toes, be sure that the perches are wide enough so that when the bird perches, the feathers cover the feet. Good luck.
