My one year old Brahma chicken is acting strangely. She laid an egg today but doesn't want to leave the nest box. I felt her abdomen and it doesn't seem as if she had and egg stuck, either. When I touch her she ruffles her feathers and makes a sound like a horse neighing, if you can imagine that. I gently lifted her and pushed her out of the nest box and she acted as if she couldn't/didn't want to stand. At dark when the other two chickens were roosting, she did not join them. What to do?