The data you provided is not sufficient to detect the exact cause for the headache.
Possible causes for headache include: migraine, neural disorders, hypertension, eye disorders, cervical spondylosis, brain tumor and dental pain that has already spread.
The exact location of the pain might be helpful.
The characteristic location for migraine, for example includes only half of the face. Headache caused from neurological disorders are located in the area for which the certain nerve is responsible. Dental pain that has already spread is easily detectable.
Pain originating from inflammation of the sinuses depends on the location of the inflamed sinus.
Presence of other symptoms such as: diplopia (double vision), nausea, vomiting, vertigo, might be of great help. How long the headache is present and whether it is constant or temporarily relieves is also important. The quality of the pain (dull, stabbing) should be reported when examined by doctor, too.
As you can see, there are many possible causes for headache. You might want to visit your family doctor for basic physical examination. He might refer you to a neurologist, ophthalmologist, an Ear, Nose and Throat specialist or specialist in physical therapy depending on the most likely cause for the headache.