I feel way out of my depth trying to talk about this condition, but I feel like at least getting some eyes on it is somewhat nice either way?
I'll at least say that what's depicted in the comic (debatably poorly), is that it took a little bit before my bedbound-crash rammed into my face. Either way, a person with ME\CFS needs to be extremely careful with exercise, and what kinds they do. Potentially can't do any at all or risk PEM or a Crash.
A person doesn't need to have all the symptoms to be experiencing PEM, but you will get more and more as you strain yourself. And repeated triggers of PEM is bad. Our options and way of living are pretty limited by that.
ME\CFS messes with a lot of the systems in your body. But it doesn't show on bio markers tests runs through... So what little of treatment there is, is mainly symptom management.
Grading the severity of ME\CFS Source for symptoms