I have recently (beginning of this year) begun to occasionally develop very painful blisters on my toes and feet, especially around the toenails, joints, and occasionally the arch of the foot. Very occasionally I will have a similar painful bump on the base or joint of a finger. They start as small, hard bumps that spread, and seem to be fairly deep in the skin. They have a white coloration inside with red irritated skin around them. If they're on my arch or hand they have a white ring with red skin inside and outside. They are small, never getting larger than a centimeter at most, this is usually on the toes when several kind of mesh together. Otherwise they're no bigger than the head of a sharpie marker. They will pop up for about a week or two, then disappear, only to come back a month or two later.