I have headache these last 2-3 days. most painful in neck and shoulder area. what do i have?

Headache: A lot of things can cause a headache and trying to figure out why you have one is almost impossible. However, i can say from an emergency prospective i would be concerned if you had a fever, it kept getting worse, it had a sudden onset, it hurt severely to move your neck or look at light, and/or it is "the worst headache of your life". If so get to a doctor asap.

Tension or muscle : Strain is a common cause of pain in the neck/ shoulder area. Other causes- strenuous exercise, arthritis, uncontrolled blood pressure, poor posture, etc. See your dr if symptoms worsen. Take care!