My 4 year old daughter woke up with neck pain. she says it hurts to move it up and down in a "yes" movement. what could this be? do we need to see a doctor today?

See below: This simply maybe muscle pain from sleeping funny. If she does not have a fever, headache, sore throat, and she is able to move her neck, i would give some tylenol (acetaminophen).

Muscle spasm: Young children sometimes sleep in the same position all night and will have neck muscle pain in the morning especially if head was held in an abnormal position. They will have pain when they try to turn their head. This will usually improve as the day progresses. If pain lasts greater than 2 days see your pediatrician.

Massage: Is this a recurring problem or one time problem? Stretching with a massage oil like sweet almond oil. Also try a rub like vicks. If it doesnt work, a gentle stretch with a licensed practitioner is in order.

I'd worry if...: If she seems okay and actually can move the neck in all directions, it likely is a strain and you can use some Acetaminophen or ibuprofen. If she has a fever, can't swallow properly or is actually unable to move the neck, i'd get it checked out today. There are some rare infections of the back of the throat that could be serious if left untreated.