My White Leghorn Hen, Tammy Sue, looks sick. She hasn't laid an egg in a while, is loosing feathers on her head, and looks sick in the face. She has been this way for the past few days. My chickens are normally in the coop all day because where I live its usually negative temperatures all day. Tammy is usually the alpha, next to Lucy. I know my chickens very well and this isn't Tammy. She's up and walking, eating and drinking. I'm not sure if she is starting to molt or what, but can somebody help? She is almost one year old(She was born on May 21st) and has grown up with five other hens of all different breeds. They get along very well and they haven't turned cannibalistic, yet. In the winter coop, I have a water heater, two heat lamps, a food pipe, a bucket full of water, a normal light and four nesting boxes. I use pine shavings for their floor and leaves, shavings and other materials for them to make their nests out of. We have a vent in the coop so the air can circulate and won't get frostbite. Tammy stopped laying eggs a while ago, and I thought it was just because it's the winter. Somebody help!