If you feel a dull, steady pain that feels like a band tightening around your head, you may have a tension headache.
If you feel throbbing that begins on one side and causes nausea or sound/light sensitivity, you may have a migraine. Visual disturbances, such as flickering points of light, may precede the headache.
If you feel a non-throbbing pain around one red, watery eye, with nasal congestion on that side of your face, you may have a cluster headache.
If you feel a steady pain in the area...