Chickens can be very resilient, but she might have a partial dislocated neck. I would recommend a trip to a vet, check to see if they know anything about poultry.
I would be tempted to see how she goes, have normal hen food and water available and keepin a box but in a room without heating as she could overheat.
The fox will be back, they can climb wire as well as dig in next to fence wire. Check perimeters for disturbance and shut pop hole at night.