Blair Sorry to hear about your struggle, and welcome to this board. In general, it's a super informative place, if overloaded with those desperate for solutions (of which I am one). Welcome to the club, even if it's not one you had hoped to join
There are a dizzying number of potential triggers for everyone, so it's tough to track down. The usual suggestions are to avoid monitors using PWM (pulse-width modulation - flickering the screen to reduce brightness instead of having a backlight that can actually be dimmed), have good background lighting, sufficient distance and contrast between monitor and wall behind it, night shift / night light / blue light glasses, etc. I'm sure you've already pursued all of that.
One thing worth trying that you may not have yet tried: if you use a PC, install Ditherig. It's freeware that shuts off temporal dithering, which is pixel flickering to create in-between colors not in the monitor's native palette. A number of folks here are suspicious that's what bugs the eyes, and that it's become more common in the past few years. That + the things mentioned above + the general health recommendations (vitamin D / avoiding nutrient deficiencies + exercise + sleep) seem to help me. I just got a new Macbook Pro for work that seems to be bugging me still - I think the dithering is a thing on it, too, though I love the color temp adjustment of its "true tone" screen. But, Ditherig + blue light glasses seem to work on my home PC that used to wreck me.
In any case, best of luck. Hopefully you find your silver bullet; unfortunately, many here seem to find there may not be any one fix-all, but the cocktail of general health practices and avoiding abrasive settings/hardware make life tolerable.