We have a buff orpington chicken about 4 months old now acting very peculiar. She didn't go into the coop with the others at dusk but stood with her head under her wing, not really aware when we approached her. We have her inside now, she has her head down and sometimes makes some noise but doesn't eat or drink. The weather has been cold here but the other chickens are fine. She should be fine in 10 degree weather. Any ideas ?