A couple of weeks ago my 7-yr old hen died of unknown causes. However over the past couple of months she had lost a lot of weight. I tried worming here and feeding her by herself to make sure she got plenty to eat, but she wouldn't gain weight. Some of the day she would sit around and pull her head/neck in, and sort of fluffy herself up, like she was cold. (and it was cold some of those days, but the other chickens didnt do that) She also slept on the coop floor next to a rooster. The rooster is acting the same way and has lost some weight too. Ideas?? Also I have one hen who is off to herself, not really eating, and has a dirty butt. Her weight seems ok. She doesn't seem to have an appetite. What should I do for her?