Hi Bryan, welcome.

I suspect what you're describing is pressure on a nerve that is either causing or interfering with a signal, similar to the way pressure on a nerve can cause a limb to "fall asleep". I'm reminded of the old cornball joke:

Patient: Doctor, it hurts when I do this.

Doctor: Then don't do that.

I do know how chronic headaches can be baffling and infuriating. The nausea/vomiting factor suggests (to me) that there may be a migraine element. It is not uncommon to get both kinds of headaches—tension-type and migraine—separately and/or together at the same time. I get those, and they're among the most difficult to treat, as each type requires a different type of intervention and choosing the wrong type of intervention can allow the headache to get a stronger "grip".

My suggestion—if you haven't already tried it—would be to seek out a headache/migraine specialist (i.e. board-certified in headache medicine); not just a neuro who says they can treat headaches (I bounced around through several neuros who made that claim, and none of them knew their .... y'know. Preferably one whose practice is limited solely to headaches/migraines—they treat nothing else.

Doc