You could try giving her a little aspirin and see if it helps. It gets really tricky if there's an injury higher up in the leg (thinking happy thoughts) - not much we can do in terms of splinting if it's not lower leg because try as I might, I haven't managed to train a chicken to use crutches yet.
But, you could consider creating a sling for her so she isn't getting up and down on what seems to be a painful leg. Do a search for "chick chair" and or "chicken sling" and there are lots of fun ideas on how to prop her up. I've even seen underwear used ...
Edited to add: A sling provides relief in 2 ways - keeps weight off the bad leg, and it gives the good leg and all the muscles she's straining to move herself from spot to spot a break by supporting her body mass.
But, you could consider creating a sling for her so she isn't getting up and down on what seems to be a painful leg. Do a search for "chick chair" and or "chicken sling" and there are lots of fun ideas on how to prop her up. I've even seen underwear used ...

Edited to add: A sling provides relief in 2 ways - keeps weight off the bad leg, and it gives the good leg and all the muscles she's straining to move herself from spot to spot a break by supporting her body mass.

