My Leghorn hen, who is over a year old, has whitish diarrhea that leaks from her bottom. It started out thicker and of a dark color and stuck to her feathers. She promptly pulled out her feathers on her behind. So now her butt is red and sore looking also. She is eating, drinking, laying and acting normal. No changes in diet etc. This has been going on for a few weeks. No other chickens are having this problem. Any ideas?