Quick google search said Tuna is a good source of Selenium. As PP have said, Vitamin E, and Selenium may fix her right up. I'd also include a source of B vitamins, and really, a good multi vit. Other thread searches for you to look at: Star gazing, crazy chick disease, wry neck, Vitamin E encephalopathy. I had a hen who was a moon walker, but only during times of stress: molting, cold weather. I'd give her some Poultry Nutri drench and that would fix her right up until the next episode. She was a wonderful layer.

I definitely agree with the post I have quoted. I feel as though this will definitely come in handy for you and your hen.