One of the hardest things on chickens is stress.
I've had two hens completely paralysed through stress.
The story of one is below. I've linked you to it so that you can have some idea of what Dandy and I went through to get her mobile again. It may give you some ideas about how to go about...
Keep her warm and stress free. Feed her tinned fish, scrambled egg and anything else she will eat. Take her out daily, in the pet carrier if necessary so she can see the rest of her group. If you let her out for a while you need to stay with her and prevent her trying to move around.
Explain to...
She shouldn't have been out and about and she shouldn't be on painkillers.
The fox attack has just exacerbated what was already a debilitating condition.
What she needs assuming it's a muscle strain or temdon injury is rest and minimum mobilty. That is in part what the pain is for, to discourage...