3-4 day old chicks-one struggling!

I received 15 chicks from a friend who hatched them with an incubator. There is one precious little one who is struggling. She seems to be breathing faster than the others, and kind of waddles when she walks. (more so than normal) She is eating, drinking, and peeping normally. I started her on Polyvisol last night, and think she might be somewhat improved, but not in her breathing. Her legs seem a tad bit shorter than the others, also. Everyone else is perfect! any thoughts?

 

Have them all on vitamins, and medicated feed. She is a tad bit better this evening. Only time will tell, I guess.