My baby chick something is wrong

okay so we've had some baby chicks ( not our first) and the other ones are fine and growing like weeds except this one...ahe won't really walk and when she does it's a struggle for her and also she does this weird thing with her neck sometimes almost like stretching it out and im worried that she might have pectus carinatum because her chest just doesn't feel or look right...i know it's not splayed leg...and her vent is slightly protruding as well but it's all still intact help please!.