what is wrong with my chick?

[L*A*G*]

my chick just started doing this last night.
it will stay to it's self and it will push it's head as far back between it's legs and back up into a corner and it seems likes it sleeps (way too much). it is 4 weeks old today. all the rest of the chicks r just fine.
do u know what to do?

 

[Skip]

Need more information.

Is it injured?

Does it have any other symptoms? The runs? Nasal Discharge? Are the other picking on it? ect.

I can't tell what to do with your description.