8 week old chick not growing or walking

[kerrybaci75]

Ok this is my 2 flock I have 4 americanas 2 new hamps and 2 black sexlinks and 1 that I am not sure what she is, this is the one I am having problems with. She eats and drinks but is alot smaller then my other babies. She also seems to have a hard time walking she hobbles around then just lays down, she is getting trampled by the others. They dont pick on her yet, but I know they may start, my question is what could be wrong with her? The others seem fine.I will post a pic.

 

[kerrybaci75]

Here is a pic of her she is the white one