I have a hen who is 10 months old. She was laying eggs regularly but now she stays in the nesting box all the time. She is eating and comes out at least once a day to scratch around for food but then goes right back to the box. However, there is NO egg. This has been going on for a few weeks now and I'm getting concerned that something is wrong. When I go near her she puts out that teradactle scream and raises her back feathers..... she does the same thing when other hens or the rooster comes near her. She's also creating another problem it seems where the hens pick on her when she comes out, sort of like she has seperated herself from her flock. Any ideas?