I have a chick who is around 11-12 weeks old and has developed a limp. I've checked for a wound and can't see anything. My three new chickens free range during the day and are in a rabbit cage, covered with a tarp and up on a table at night. She seems to be leaning, but I think maybe that's cuz it hurts for her to bear weight on her foot. My neighbor, who also has chickens, said that there is a disease with symptoms like this. I was hoping that sometimes they just get hurt and need time to heal. When should I become concerned that it could be more than that?