Thanks for the responses!

Terry, I live in Savannah. I don't think I'm going to be running the
marathon now though (see below...)

Luc, I think you hit the nail on the head. I have overdone it, I
think I went for a marathon build too fast and too soon. It turns out
my little pain is bigger than I thought and may be a stress fracture,
so I've got to take some weeks off and regroup.

Ken Bob, thank you so much for the recommendations! I will take it
easier when I start back. I will try incorporating some totally
barefoot running.