It sounds more like a blister than a callus.  Calluses don't hurt.
They are thickenings of the skin and can be ground off with a scraper.
It is odd that a blister would last for two weeks. Perhaps you should
go to a podiatrist and have your feet checked out.  You could even go
and get a pedicure and see whats up.  That might be cheaper than a
podiatrist.  Men can do that too.