Chick just standing still

[Serphs]

Hello, we are raising 15 chicks in a wood box in a old chicken coop where our old chickens rooster before we moved them. One of our chicks has not being moving very much or making sound. She has taken a drink, but she seems lethargic. Help please?

 

[SAMnELLA]

How old is the chick ? Small chick, maybe has pasty butt ? An egg layer, maybe egg bound ? Need more info and hopefully more experienced people can help.