I've woken up and can't turn my head one way. what would cause this?

Muscle strain: Sleeping in abnormal cervical position. Motrin otc hot towels to neck. If no improvement by morning call physician. Muscle relaxant and stronger antiinflammatories are helpful.

Muscle tightness: If you sleep in same position for too long, muscles become tight like a cast on elbow would leave you in pain when cast removed and starting to move for first time.

Torticollis: Torticollis is a fancy, medical term for a stiff neck. This can be caused by a number of things including sore, stiff muscles or even mis-alignment of neck vertebrae. As a musculoskelatol problem, several different folks might be able to help including massage therapists and osteopathic physicians. If you have a stiff neck with a fever, you should see your doc to rule out a nasty infection.