Yeah, my guess is it's all downstream I guess? So hard to know. It feels like my dopamine levels are off, but if I work too much on the computer I initially get a 'pressure' feeling in my head. That usually dissipates when I stop, but is followed within maybe 12 hours by digestive problems - acid reflux, lots of gurgling, etc. After that, usually reflux coughing and then headache or migraine.
So for me, my very vague guess is: starts with some neurological problem, which then leads to gut issues, which further causes mitochondrial and exacerbated neurological problems.
Obviously I don't really know, though. Physical activity leads to muscle pain that forces me to stop before it usually causes PEM, but if I push through, that will trigger it as well. Mental exertion of any kind reliably triggers PEM.
I have to try cumin separate from food - I often add extra, but maybe next time I'll try 1g or so and see if it does anything. When I tried that before, it seemed to help my PEM by 20% or so - noticeable but not a huge difference. I do like to revisit things.
I'm kind of interested in trying St John's Wort or Kava or stuff like that, since it really does seem neurotransmitter related in many ways.