This could be a sinus headache or a migraine. Do you have nasal symptoms with it? Have you tried over-the-counter nasal decongestants when this happens? They may help if that is what it is, just be sure not to use them too often because you can get re-bound sinus pressure.

If it's a migraine, you'll probably have sensitivity to light, noise, and/or smells, some have nausea and even vomiting.

Either way, you should see a doctor about this. If you think it's sinus related, go to your primary doctor or an ENT (Ear, Nose, and Throat doctor). If you think it's a migraine, go to your primary doctor or a neurologist who specializes in headaches. Write down all your symptoms, when you get them (what happens before), and any questions you have. There are treatments for both of these. You don't have to suffer with these headaches.

I have the same exact symptoms. MRI, went to the ENT, CT-scan, EMG (neurological exam), etc..... Sinus pain is almost never unilateral. Is it possible you clench your teeth or grind them at night? Sleep disorder? Put your fingers on the back of your neck, right below your skull. Open and close your mouth and feel the muscles in the back of your neck as you do this. Any connection, you think? Hope this helps...