Hi again, MistressLex. I submit the uncanny likeness to a real life sequence that sometimes happens to people of great vision, to those who *see* and love the awesome potential in humanity (the wash of faces both real and not), who dedicate their live energies to helping fulfill this potential--only (and often) to have it backfire on them, to have their best efforts result in some of the more vicious humans turning on them and denying the very insights that would elevate them in the long run. Very often the rejected visionaries choke on their own tears (or blood), and what-could-be becomes what-never-will (at least not in their lifetimes). This is a very soul-deep pain that can manifest in/on their actual body.
So, perhaps you are or are supposed to be one of those messengers, or like me, have seen/empathize enough that you dream of them and get to more deeply know their calling and their failing. It's a bitter subject, and one that has caused no end of frustration among some (and often with bad results as they let their frustration get the better of them). It is an epic, behind-the-scenes struggle of humanity: do we evolve into who we were meant to be (the most successful aspect of our potential), or do we waste away for continued generations? If you felt an abiding angst and the overwhelming mass and momentum in wrong directions, I would be more certain this is at least one accurate explanation (at least of a vicarious experience-summary of another). Anything more you can draw out of your experience?
(I have also "blacked out" inside my dreams before, sometimes with a good kind of overwhelming and sometimes with a bad one--both kinds often linger for as long as I can remember the subject that caused the feeling that makes me effectively pass out from within the dream. It's a fascinating if unpleasant experience.)