That is known as wry neck or torticolis, and can be a symptom of head injury, vitamin deficiency, and can be seen in Mareks disease and other diseases. Some chickens have a hereditary predisposition for wry neck. Chickens with wry neck sometimes may run in circles or walk backward. Most people treat with vitamin E, thiamine,and selenium, a mineral that helps to utilize vitamin E and if found in egg, tuna, seeds, and nuts. Many use a vitamin E capsule, and open it over food one a day. Then you can use a regular chicken vitamin in the water or give Poutry NutriDrench or PolyVisol without iron. Chicken vitamins are cheaper than Polyvisol usually.
Make sure that she gets enough to eat and drink. You can mix chicken feed with a lot of water, and add some cooked egg for selenium, then hold her to eat 3 times a day.
