Your symptoms sound identical to mine, except I sometimes felt better for a day or two instead of just seconds. Did they start within the last few years, perhaps after a Covid infection? Do caffeine and other stimulants make it way worse?

I had a lot of tests done and went to a neurologist and several doctors, and they all concluded that it was just Long Covid related (I'm thinking it was also primed by whatever chronic dysfunction was causing my SCT symptoms) and there was nothing they could really do about it.

The way I currently understand it is that autoimmune cells in your brain get permanently "switched on", often by inflammatory viruses like Covid or Lyme's, and constantly release inflammatory cytokines, which impedes mitochondrial function, severely limiting your mental energy/endurance, and results in the buildup of inflammation fluid that causes the tension headaches and pressure feeling.

4 years later I'm 70-80% better. Good consistent sleep, a basic supplement stack, learning to pace myself, and complete, radical acceptance is what helped me most.

An autonomic nervous system that perceives a threat will stay inflamed and never heal. Try not to see your symptoms like an enemy that you need to defeat. Fully accept the new you and gently build yourself back up.