It turned out I was allergic to the iodine used to sterilize the injection site on my knee. I spent most of three weeks in bed or on the couch, curled up with a lap top or my Nook.
I would have been angry about the mix-up in light of the urgency, and then mad at myself for being upset over something we encounter fairly frequently when tests are ordered. Waking up from a nap to hear about it wasn't upsetting at all, because Jennifer said, "The important thing is someone will try to find out what's wrong with me, and I'm not sick as a sign of being crazy. It's something they can fix when they find out what it is!"