I'm not sure if I have the same feeling as you have all described. It certainly comes when I am most tired and have "overdone it", whatever it is, but I would not compare it to a vibration. The sensation is as if I were crumbling inside, falling apart internally (in my thorax and abdomen) over and over and over again, which may sound minor, and almost ridiculous, but it is worse than any pain I have ever had, and I've had some. It lasts no more than 15 or 20 minutes at a time, fortunately, because if it went on longer I swear to God I'd lose my reason, or jump off a tall building. Nothing works on it except rest, and patience, if available. It doesn't come as often now as it did when I first fell ill, back when dinosaurs stalked the earth, and didn't know my limitations, or didn't want to know them.
I also get trembling in my hands, klutziness, general muscle weakness, etc., but this inner crumbling is a quite distinct phenomenon.
Parvofighter: The material on blood flow is fascinating. Thank you for the reading suggestions.