I have a young Wellsummer pullet about 3 months old. She was part of a group of 8 chicks of mixed breeds I bought to increase my flock. When the other chickens are out scratching and pecking she will walk to the area and lie down. She pecks near where she lays and if they leave her area she will walk or run to them and soon lie down again. I have noticed a slight skip to her run and a bit of gimpiness to her walk but she uses her both her legs equally. She also lies down in the coop. Her eyes are bright and clear, her feathers are not ruffled or dull. She seems to eat well. I have examined her feet and legs and found no obvious cuts, splinters or abnormalities. Any ideas what causes her unusual behavior?