Wow, Spdsk8trgl, you sound a lot like me.
The afternoon headaches used to be a daily issue, now they tend to be more morning or middle of the night. They did usually feel better lying down (no leakage from nose/ears before or during).
The pain being more constant and posture neutral fits my pattern too. I am more aware that now there is more of a posture element to my headaches than probably before. I too had migraines, and used to think these headaches were migranes that were “different.” Now I know they weren’t.
The mast cell (zyrtec/zantac) treatment is definitely helping me profoundly too.(Thanks Dr. Driscoll!!!)
My headaches are worse slouching or laying down a lot of the time. I did notice the couch thing from laying down, not supported properly under my neck/head. Reading, doing my nails, or any task head forward is very painful and can induce pressure and a headache. (Sometimes it goes away if I take steps such as adjusting position and/or putting heat on my neck.)
The worst thing for me for inducing a headache and/or neck pain is leaning forward. Loading/unloading the dishwasher is the worst. I’m learning to wear the cervical collar while I do it, and that helps. It’s definitely something I’m doing to my neck combined with leaning forward.