Where do you live? Is it wintertime and cold, or is it warm there? It looks like pecking from other chickens, and there even might be a little frostbite on the tips of the comb, but also could be pecking? The while near the dark marks is probably just healing taking place where there were peck wounds. I would either leave it alone to heal on it's own, or apply some coconut oil to help moisturize the dry skin. This does not really look like favus or a fungal infection to me, but others may hav other opinions.