Sometimes the feeling as though you are walking on a pebble can be due to a deep callus, called a porokeratosis.  Other times, this can be due to sesamoiditis.  Pain in the ball of the foot near the big toe joint can be due to loss of the protective fat pad that we are all born with.  This fat pad atrophies, or thins, as we get older and put pressure on this part of our foot.  When this happens, two little bones called sesamoids are predisposed to taking up more shock absorption and this can lead to pain and damage of these bones.