So, I emailed everyone with whom I had obligations today (and there were quite a few of them - it's been a week like no other), and told them I couldn't make it. For once, I actually felt reasonably justified in taking a day "off", mostly because it hurt too much to do much, and because I've been running myself ragged the past few days getting everything done. And the day hasn't been a complete waste - I watched the movie I need to write a paper on for Monday, and now have an idea for the paper, which I didn't have before. So, all in all, not as much done as I would have liked, but still, better than nothing.
In the meantime...this keeps up tomorrow, and I'm going to the Health Center to see what they can do for me. It's been hard to get anything down - for the most part, my nutrition has come from some little cookies and humus on whole-wheat flour tortillas (which, by the way, is a fantastic snack, I've discovered). This displeases me. So does not feeling fully awake. But, meh, we'll see what we can do.