I have this 1 leghorn that shivers as if she is cold. She sits by the heat lamps when she comes off the roost. I think she eats and drinks because when I take treats to them she comes to then she goes right by the heat lamps again. She gets on the roost every night. Just sits there shivering. What could be wrong with her? She is the only one that does that. At least the other hens don't pick on her like they do my buff orp that won't come out of the nesting boxes and they sure are mean to her. Not sure how to stop that either. Should I give them some medicine? She isn't coughing, sneezing, or anything like that, just acts like she has got a chill and can't stop shivering. What could be wrong with her?