I'm sorry to hear about your bird, it doesn't really sound like wry neck to me(Unless I've missed something and her neck is bent under her body. Unless your vet did a fecal test for Marek's then I wouldn't rule it out completely.
Keep going with the vitamins, when one of my pullets broke her leg I put in her a chicken stretcher . Just make sure that her legs being back in the right position doesn't cause her to much distress, and if you do choose to go the stretcher route, then make sure that the fabric is VERY well attached to the wood. I'll add some better quality stretcher pics later, I have to go out for a little while
(siblings are going to dance lessons)