I received two 11 month old hens from a friend and added them to my flock of 4 on Tuesday. 3 grew up together and are the same age as the two new ones. The 4th was added 2 months ago appears to be about 5 months old. She does not lay yet. Wednesday when I arrived home I realized one of the newbies was limping. I checked for injuries to her foot, leg, wing and can find no indication. Could it be sprained? How do I treat it?