I've given my feet weeks to heal, and it's clear that they need more time.
I've been running extremely lightly (2-3 miles 10 min/mile pace) every other day and the results are pretty consistent- I run, and the pain worsens. I even tried running on grass and dirt trails to see if it would make a difference, but no dice.
At this point I don't know what's up with my feet, but I feel I can't train anymore. I'm not willing to risk permanent injury. I still plan to run the marathon, but I'm not going to be in the kind of shape I'd like to be in when I run it.
Hopefully my feet are completely healed by then. They've got 19 days.
Until then, I'll be doing a lot of biking. It's not nearly the same thing, but at least it gets the heart going.