One chicken is smaller

[akchickens08]

We have 8 chickens, various breeds, and one is a buff Orpington. She is noticeably smaller than all the other chickens, they were all born at the same time. She also is very calm and doesn't move or get up very much. When she does get up she has trouble walking and kind of stumbles around. Does anyone know if we can help her?

 

[Hillaire]

put electrolytes in the water also give her a look over and see if you notice anything like a hurt foot or anything really. how old are they? you said chickens but it sounds like chicks?