HELP! fox attack

We have 4 isa browns about 1.5years old. Im in need of some education regarding a sick chook. We woke at 5am to the noise of a chook in struggle when we went outside 'Cinderella' had sadly passed away and dragged to the garden bed and poor 'Dora' was alive but not moving anything but her eyes. The other two were ok. We took Dora inside and kept her warm. No sign of blood or wounds anywhere except a few missing feathers and a tiny blood spot on her crown. Upon assessing her she cannot use her right leg and her neck is floppy but she is able to turn her head. She isnt really interested in food or water but i have forced her with pellets soaked in water and water via a syringe. Only small amounts every hour or two since as she gets upset. I just checked her and she hasnt pooed yet and its been over 8 hours and also her crop is full. Ive googled stuff but im unsure what to do. Is she suffering? Should i persist or take her to be put down at the vet? For all you chicken lovers out there please help me. I dont know what to do and i cant stand watching her just lay there and blink because i dont know what I'm doing. HELP ME PLEASE!!!!
Thanks chels

I would honestly call the vet and tell them what happened and see what they say could be wrong with her but if she isn't better by tomarrow after noon I would take her to end her suffering and or if she doesn't get any better at all i would try and put her I a leg brace and see if she will try and hold her self up a bit if her crop isn't empty by tomarrow morning try and massage her crop to get the food and water to drain and just by getting some food and water could really get her feeling better