One day a couple of weeks ago, out of nowhere, one of my hens bit my hand while I was feeding them sunflowers seeds out of it. Since then she has gotten worse, often attacking my ankles, the backs of my knees, my hand when she can reach it, and even my heel as I'm walking out of the chicken run. She attacks me on whatever skin I have exposed (I thought wearing pants would solve the problem, but apparently I need socks and gloves too), both biting and scratching, usually when my back is turned. I don't want to get rid of her because I only have two chickens left after an illness last month and she is perfectly civil to the other hen. I'm getting afraid to go into my own chicken run and shouting "bad chicken" (she ignores it) and lightly smacking or kicking her (I got bit on the hand for doing that this morning) are not deterring her. Could this be a medical symptom? Is it something I did? Thank you for any insights you can give.