What you are describing is most likely Wry Neck. It is easily cured, if you catch it early. What Fried Green Eggs said will help. Get some Save-A-Chick and give it to her, by dropper, every day, as often as you can. If you can, get some Beyond Tangy Tangerine powder. It's a complete multi-vitamin, mineral complex, and really helps a lot.
I had a Silkie pullet with Wry neck, and now she is 6 months old. Good luck!