I was on the outside of my chicken pen, when one of my hens ran down the run, and attacked another hen, she knocked her to the ground, and pecked her head several times, bringing blood. My rooster tried to protect the hurt hen, but the attacker kept attacking and knocked the rooster out of the way. I have the hurt hen separated and giving her stuff to build her up, and I have the attacker locked up in another cage. What caused this hen to attack? And what should I do to the attacker? Please I need help