First of all seperate her from the others. Blood drawn only makes the pecking worse. Clean the wound and give her time to heal. Give her lots of protein to help promote healing too. Poor baby! Chickens are very resilient so with some tlc she should be fine! Good luck to you!!
Awww! Yes, I agree with the poster above. But if you can keep her in an area where they can see each other it would be better because then, when she is healed and you put her back with the others, they will be familiar with her and won't attack her because she's a stranger. But definitely get her away from the others and use some antibiotic cream withOUT pain killer! Good luck to her.