C.M.
I've dealt with practically every foot problem... sounds like a Neuroma or a stress fracture. I've had both in opposite feet just above my toes. The stress fracture was on the top and the neuroma was on the bottom. Not much you can do for a stress fracture except ice, but the neuroma can be given a steriod/hydrocortisone shot (which hurts like ...) See a podiatrist.