So far, so good. I read up on it like crazy, and one of the articles recommended trying some athelete's foot creme. So we thought we'd try that first and its working. I'm willing to prove it by posting pictures. I should post pix anyway, in the name of science. The articles I read said that it can take a week to clear up, and that is what I'm seeing, but there is no doubt it is going away.
We made other changes, the most important one is we don't water him near his sleeping area, so the sand in there is losing moisture. Of course, we also cleaned his cage, but I don't think this was an issue, because he either spent his time inside his (clean) sleeping area, or on a clean rock.
It should be noted that he has been lethargic prior to this, and it is probably related. But now he's perkier. I guess because we're knocking out the source enough for his natural immune system to do the job. From his rate of recovery, I believe that if the spot was much bigger, they might not have the natural immunity to overcome it with just a topical creme.
Don't know if it is related, but yesterday was the first time we were able to put it on without him trying to bite us.
Will post pictures later this week.
Steve