It sounds like she may have lice or mites crawling around. Can you look her over for that? Permethrin garden dust or spray from your feed store will treat lice or mites. Repeat in 10 days to get newly hatched ones.
Her eye looks to be crusty and shut. I would apply a wet warm washcloth as a compress to her eye for a few mintputes to get the eye open, so that you could take another picture of what is in the eye. Is ther pus, bubbles/foam, and look to see if the eye is intact. She could have been pecke in the eye, but she also could have some signs of a respiratory infection.
The head shaking could be partly from lice or mites, a respiratory infection, but it also looks a bit neurological at times. Could she have been pecked on her head or injured? Vitamin E 400 IU softgels and 1/4 tablet of human super B complex vitamins can be used to treat neurological problems.