Sorry to hear your plight. I can understand as I have had tension headaches for 28 years now - but probably not as persistent each day as you.

A key path to take is what you are already doing - calm the mind and body. When in pain, the sympathetic nervous system dominates - the parasympathetic nervous system is slowed down. The former can trigger adrenaline and cortisol which, if sustained, are toxic to the body. The parasympathetic system enables digestion, calms the mind and body. And pain. If we dwell on the pain, the mind can catastrophise and thereby amplify the pain.

Mindfulness and meditation are key tools for calm. Just sitting in nature with no reminders of urban life is very calming. Equanimity is vital as is acceptance - they are linked - we accept and observe the pain and not buy into any narratives the mind might want to add to the pain as explainer. Often these are false narratives.

I can awaken in the small hours at night and have the terrifying feeling of a panic attack. For hours. Dying can feel like a most welcome relief. I observe and relax - as much as the pain permits. Invariable, when I finally awaken in the morning, I feel to have slept well. There seems to be no residual effect of the attack.

A super important factor here is that the body tends to manifest the mind's perception of how life is. So if we relax and do not create a feeling that we are deeply struggling with pain AND that we create a feeling that the pain will pass and we are therefor on top of things, pain can calm down.