I need some input... My Speckled Sussex have been with me for 4 seasons. They all appear healthy and are happily laying eggs. But all of the sudden one of my girls (Olive) is relentlessly attacking her flock mate Nell. Yesterday I found Nell in the nest box with Olive stacked on top of her, at first it made me laugh, but then I saw the blood. Olive's claws had ripped Nell's eyelid open. Now today Olive is running after Nell and jumping on her back, relentlessly pecking at her head. Nell is doing her best to run away from the abuse, but Olive just keeps it up. As with all chickens, I know there is a pecking order. But for years my flock has been quite peaceful with no major conflicts and no major disputes. Why is this happening so suddenly? Could something be wrong with Nell that would cause Olive to go ballistic? Do I need to separate them somehow for a time, or would that only make matters worse?