The verdict is in. My upper hamstring muscles are torn. That explains the constant pain. The good news is that I should be able to run again, assuming I can heal properly and keep from chronically re-tearing them. The doctor has recommended stretching. So more physical therapy and yoga, I guess.
He also recommends going slower -- as in not trying to do so much so fast. I didn't have the heart to tell him I could barely run a mile outdoors after four months of training, and had to work up to even that sorry distance in one minute increments. I'm not sure how much slower I can go!
There's an upside to this, though. At this rate, by the time I can complete a marathon I'll probably be in the over 90 age group and might have a shot at winning! Something to look forward to, I guess.
Anyhow... My training will continue. Slowly. Painfully. But the dream remains alive!