Between emails, facebook comments and messages, conversations, and internet research, I've come up with several more exercises and stretches for my back, which seem to be having a positive effect. At the very least, I'm not in the state of misery I was all weekend. The suggestion that it might be my upper trapezius and/or rhomboid presents a likely cause of my problems. This picture shows the muscles that I swear I have been feeling for weeks.
For those who might be interested in stretching, the Mayo Clinic has a nice set of back exercises here, although I'd been doing most of them for weeks. Oddly enough, the exercises below - specifically number 5 - while simple, really seem to have made a difference. I found them on ideafit.com. I suspect that my students might be wondering about my tendency to do #5 in class.
And I'm going to see about going to an orthopedist later this week.