A 6 month old cockerel is also dealing with overactive hormones, and he MAY have been trying to mate with the hen. He may have tried it repeatedly. This can result in the feathers being gone from the back of the hen's head, and also the blood on both of them. If she resisted, then he may have gotten ahold of her comb as well.
Young cockerels haven't learned the "art of chicken love" yet, and they are clumsy, forward, agressive, and lack skill. They haven't learned to "woo" the hens. They also lack the respect of the hens, which can result in what you described. He probably needs to be separated for a few days, and then put him back in and observe the flock. Hopefully, if this has ben the case, he will learn some manners. Having an older, respected rooster in the flock teaches the young buks manners to some extent as well.
Just another possibility.