i have a 3 yr old leghorn hen. Ive noticed her but feathers are picked out and she has a really messy rear. She hasnt laid in about a week. she still drinks and eats good and plays with other chickens most of the time, but sometimes she seems to get tired and she will just lay around i wouldnt really call it it lathargic because its not constent. any ideas on what this could be and what i should do? any help is appreciated.