I haven't treated wry neck myself, but it can be a symptom seen in a head or neck injury, vitamin E deficiency (usually in baby chicks,) and sometimes with certain diseases such as Mareks, avian lymphoid leukosis, and other infections that may affect the brain. It's not necessary to separate her since that is only to reduce stress and keep others from picking on her. If she seems happy loose, then she may be better off. Polyvisol is really not necessary since you can put poultry vitamins in the water. One product, Poultry Nutri-drench, and also Poultry Cell, contain vitamins including E and the selenium. Dosage is 1 ml daily given orally for a chick, 2 ml for a larger pullet, and 3 ml for a big chicken. Or you can do the other vitamins instead. Selenium is only needed in a small amount, and is found in egg, chopped tuna, salmon, nuts, sunflower seeds, and many others. How old is she? A big problem if the wry neck is severe is having to help them eat and drink several times a day if they can't.
Here are 2 good links about wry neck:
http://www.browneggblueegg.com/Article/Crookneck/Crookneck.html
https://www.backyardchickens.com/t/97121/lets-talk-wry-neck-crook-neck