Looks like wound been applying microcynAH I send closer picture.
Maybe that has something to do with why she isn't using the leg?
A side note, but if you have healthy adult chickens that are currently laying you could scramble some eggs and mash them with the back of a fork to offer her too.
I'm sorry. There are infections that can develop in joints but I'm not sure that's what we're looking at and I've never seen it in a chick. Slipped tendons usually cause the leg to twist in one direction or the other depending on which way the tendon slips but if you can see the tendon from the back of the hock joint on either side it may be that.
