Well, I just went to see the physio, and he was very helpful. He discovered that my left ankle was very weak, and wasn't giving the support it should be, and that was contributing to my plantar fasciitis (though whether it was a chicken or egg situation was unclear). But he said it wasn't surprising that I felt as if my recovery had plateued, because that's what it was doing, because the general getting-about I needed to do was enough (with the weak ankle) to keep on irritating the area. And he did a lot of poking and prodding and pushing and pulling and kneading, and then some pressing on my forehead -- apparently accupressure points associated with the ankle, and after he'd done that, when he tried pushing against my foot to test the ankle, it was just as good as my right foot, thus demonstrating that it was a nerve-signal thing and not a muscle thing. Amazing.
He was also the first person to ask the obvious question: if it had been new shoes that had caused it, then why was only the left foot affected, rather than both? So it seems more like the ankle weakness was a cause rather than a symptom, but we don't know what caused the ankle-weakness. Mystery.
He's given me some exersizes to do, and will see me in two weeks.
And in other news, my firewall seems to be being bombarded with udp/domain requests on port 53, from machines with names like **.dialup.***.nl, which makes me suspect I'm getting fallout from a firestorm generated by virus-infected PCs going boom on Friday the Thirteenth. Such an auspicious date. My firewall may end up getting overloaded. It may be wise not to do much surfing today...