So I promptly drove out to the barn, got Izzy out, and tried to lunge her in a surcingle and side reins.
Not the best idea ever. I did ok going to the left because my gimp arm just had to hold the line. Going right was bad news. Apparently, a newly-healing elbow is not ok supporting the weight and complexity of a lunge whip. Oh, and that's the side Izzy leans in on, so it requires a lot more motion.
Ugh. Apparently, "take it easy--still no heavy lifting, but do some light fingering" did not mean "you are free to return to normal activity".
Oh well. In other news, Izzy got a big ol' shoulder rub from her fly sheet. No idea how it happened overnight, since I'd been religiously checking for the slightest sign of it, but whatever. She's now sheet-free. We'll see how that goes.