I went down to pick up one of the boxes, and felt a SNAP, low on my right side, right near the bottom of the ribs. Dunno exactly what happened, but it hurt like a motherfucker. I've got considerably less pain-free movement now...guess I pulled a muscle or something, which is odd, since this was BEFORE I lifted the box.
Hopefully, this will work itself out quick. I still have a bunch of stuff to unpack tonight, and move tomorrow and Saturday, plus cleaning Saturday.