How old is she, and did she receive any vaccines as a chick? Feel of her toes in the morning, and see if she moves or curls her toes. Stand her up to see if she holds up the leg, or if she can walk on it at all. More than likely she has suffered a leg injury. Occasionally a vitamin deficiency or dehydration can cause lameness. More rarely, something like Mareks disease might be a cause of lameness in one or both legs or wings.
If no wounds or blood, by the sounds of it I think eggcessive is right. I would look into what they said and vitamin deficiencies.
Start some poultry vitamins in her water daily. Then force her to rest her leg by keeping her in a crate with food and water, but in site of the other chickens. Check her daily, but after a week, see if she can walk any better, or if she is worse. Sprains and other leg injuries can take several weeks to heal. The more time she spends with the other chickens, the easier to reintegrate her back into the flock. Let us know what happens.
Iv been looking around and she seems to have similar symptoms to Mareks disease.
Edited by xLittleSilkieX - 4/19/16 at 8:06am