Headache is the most common form of pain. There are many types of headaches, including migraine, sinus headaches, and cluster headaches, and the most common type is tension headaches caused by tight muscles in the neck, jaw, scalp, and shoulders. You may find relief from tension headaches by taking an over-the-counter (OTC) pain reliever or making appropriate lifestyle changes. However, some headaches can signal a more serious underlying condition that requires medical attention. If you experience any of these symptoms, consult a doctor immediately.