Most of your comments on yesterday's "knee" post re-confirm that which I read online, in my running books, and in back issues of RW: This is probably an IT band that has been strained. The pain is on the side of my knee, it immediately subsides when I stop running, it doesn't ache when not running, it's not inflamed, and it doesn't lock. Thus, the best remedies include all the things you readers noted I try: ice, aspirin, rest, and stretching.
I think I will do all of those things before consulting a doctor. Hopefully, with proper care, the knee strain will subside and I can continue running without any pain. For today: rest. And tomorrow, well, as my favorite heroine loved to say, "Tomorrow's another day."