Kev, have you tried acupuncture? The pressure point for headache is in the gap between the thumb and index finger. You might find some relief just be squeezing that area.

I will admit that acupuncture didn't help my TBI headache, but others have found it efficacious.

Have you been checked for damage to your jaw? TMJ/TMD are not uncommon after head injury. Neither is clenching. All of that can contribute to headache.

In my experience, the Advil will only hurt your stomach and even your liver. I've got an ulcer from the stuff.