I had headaches for a long time and it was during my initial spiritual awakening process, when I first started using my spiritual energy. I'm not sure if yours is a similar kind of head pressure but mine was just an accumulation of energy inside the head that needed grounding. I learned how to ground properly and also started using crystals and now it has dissipated. Oh, and it was also a symptom of the crown chakra opening, at least in my case. Hope you manage to sort it soon.

rose, it's amazing isn't it, you truly can feel all of the negative energy being pulled out. xxx