I felt some acute pain while walking for a half-year or so. It was increasing over that time, so I went to the doctor. Doctor said it was a papilloma wart under the sole skin, so she cut off the skin with some milling cutter(no Idea what it is called in English) and then pour some acid (even the smoke was obviously visible!) into the wound. It was painful, but FAR from how I expected it to be.