Please help. My 8 month old Welsummer hen is acting strange. For the past two days she has been sitting in one of the nesting boxes. She has her feathers all fluffed up and is making a lil chirping noise. She still continues to lay but she spends all her time in the box. She is normally quite vocal and active. She doesn't seem to have any other symptoms. She comes out to eat, but not for long, then right back into the box. Any ideas what is going on? The other 3 hens are behaving normally.