Saw the Physical Therapist this morning, and she's confident that I can beat this problem and do the 3-Day without pain. That's the good news.
Bad news is that I'm not to walk again until I see her on Monday, so there goes my sticking with the training plan for this week and next week. She wants me to exercise, just not walking, so I think I'm going to get some serious time in on the exercise bike. I'm thinking I should do 20 minutes on the bike for each mile I intended to go. The pool is closed tonight, so I won't be swimming this week, either. She said I could go on shorter walks, but if it starts hurting to stop walking.
She wasn't able to identify what the pain in my legs is, just that it isn't shin splints (which I'm glad to rule out). She determined that my right ankle is extremely stiff, which might be a big part of the problem, or just a result of me adjusting to the pain. My left ankle is more supple, which may be why it doesn't hurt quite as much.
I've got a passle of exercises to work on, some of which are familiar, some are new. The PT decided that part of my problem is weak hips, so we're starting with some exercises which should strengthen those muscles. In any case, I've got a lot of work ahead of me. I'll keep everyone up-to-date here on the boring blog, and you'll know when I return to walking regularly because I'll start posting pictures again.