I have developed a small but very painful lump under the skin on the sole of my foot. I can hardly step on the foot. I have had plantar fachitis before ( lasting for 18 months) but have had no problems for the last year. The pain is similar, but I don t think I ever had the marble type lump before. It is located on the sole, near the heal, toward the outside of the foot. Memory foam shoes were the answer before, but now even those are painful. Help, please!