My Chicken can't walk Help!?

I have a hen who is between 6-8 years old.This morning we noticed that she won't use her left leg she lies on her right side so that no pressure is on her left side.We only have 3 other full sized chickens all the rest are Bantams.She tries to walk/hop ,but she keeps falling on her face.She has always had scaly legs,but I don't think it is mites(we have treated her for it multiple times before,and it doesn't change)There is no vet around here that will look at a chicken,so don't suggest that. Should we separate her from the other chickens?