@neonsnake is it this? https://creakyjoints.org/living-with-arthritis/explain-chronic-fatigue/ I just did an internet search so I'm not sure >.<
Also, hey, I have something that sounds a *lot* like this thanks to PPCS. I have a hope of it going away eventually, bc its the result of a neurological disorder caused by an injury, but I wanted to say I feel you — both in the complete exhaustion that destroys your ability to do anything for weeks on end and even in the middle of doing things, and in being unable to explain the depths of it. The fever analogy is really good.