Can you look very closely at her foot? The way she is hesitant to put it down leads me to believe she has a foot injury. Look at the pads, between the toes, the toenails, tops of the toes. Look for any greenish bruising.
A chick can become frightened and fly into a wall, causing bruising in between the toes on the webbing. It will be very tiny and faint, but if you see any discoloration, that would be her problem. You can give her a half a baby aspirin (81grain tablet cut in half) twice a day. It will reduce both pain and inflammation.
Keeping her off her feet for a few days except to eat and drink, will help it heal more quickly. But try to keep her within sight of the others.