The source of the pain seems to be just below the ankle, but just above the foot, in neither. It might be a tendon injury of some sort, but we really don't have a clue what it is. Took me out of commission for the day, though, had to limp home, and now my foot is elevated with an ice pack applied, standard 20 on, 20 off.
Injuries suck. I don't think this is the first time I've had this injury, either; it may have cropped up before, several times in fact. But it was notable enough that I couldn't hide it like I normally would. Oh, well. Gives me a convenient excuse to do nothing.