Thank you guys she is lumping on it I checked her over 5 times and couldn't find anything. She is eating and drinking and all she wants to do lay down.
I live in Pennsylvania and it has been down in the negatives for awhile. The coop is well ventilated and warm. In the spring I am going to get a couple of more hens
I lost a couple of them when we got a bad cold spell her I bought in my house and keep her warm so she didn't have to be in with the other hens I tried to keep her alive