Help, My chicken won't act normal

[ChickenBro 07]

My chicken lately has been acting weird. She is about 13 weeks old and now seems unhealthy. She didn't want to roost last night, she doesn't chirp much now also. she doesn't move or eat much either. She seems to limp and walk slowly when she does walk. The other chickens aren't pecking at her. PLEASE HELP

 

[chcknatthedisco]

I have no idea what it could be. But I would separate her to get her away from the other chicks.