Hi there had my 5 chickens 3 month now ,bought as point of lay, they have been laying 4-5 eggs everyday but one of them will not come out the nest box she gathers all eggs up and lays on them,puffing and displaying when I go in, I picked her up this morning and she is completly bald on her tummy,do I need to take her to the vets or is this something that happens,I am new to this and quite concerned, p,ease help and give advice