Seagull
I wanted to find out if the screens that work well for me have faster or slower response times than the ones I cannot use.
Results: It seems plausible to me that a fast rise time (from black to white) causes my symptoms (headache, nausea, tinnitus). Also, very bright screens might exacerbate this issue, since these screens would have a larger total change in brightness from black to white.
The fall time (from white to black) was very similar on my least favorite monitor and my favorite monitor. It seems unlikely that fall time by itself causes my symptoms.
The experiment:
To run the experiment, I created a web page that sets the background to white, waits 40 ms, sets the background to black, waits another 40 ms, and then repeats. I measured the light output of the screen using my oscilloscope and light detector (the one described elsewhere on this forum). I measured seven screens (phones, laptops and monitors) that I like but only one that I absolutely hate ('cause I usually get rid of the ones that I hate).
The monitor I hate (HP LA2405x) had the fastest rise time, fastest fall time, and largest overall change in brightness. I tested this monitor at full backlight brightness (otherwise it has PWM).
My favorite monitor (ASUS VW228TLB-P) was actually the most similar to the monitor that I hate, but the rise time was significantly slower and the overall change in brightness was lower. I also tested this at full backlight/full brightness because that's how I use it on a daily basis.
I've attached the waveforms so you can see the difference.

