Help! Possum attacked chicken!!!

My chickens were attacked by a possum two nights ago. Luckily I was able to hear the attack and got to the chickens before any of them were killed but one of the chickens had a cut about an inch behind it's right ear. It bled a little bit but I quickly cleaned the cut and put a clotting agent on it. I noticed during the day though that it wasn't eating and thought it was still in fright but then realized that she couldn't open her beak enough to get food or water. I am able to open her beak though and have been feeding fer blended feed with water using a medicine dropper as well as using polyvisol. Does anyone know if she can get better or if maybe a muscle was cut that is used to control the beak? Any suggestions would be very helpful. Thank you.