question: I have a small lump/ round cyst-like ball under the skin on the arch of my foot. It is not a callus. Its failry dept into the foot. I am a runner and didn t know if part of my tendon on my foot has developed some odd swelling growth or what. It is not really painful but my whole arch has been hurting me on and off for a year. I just thought it was plantar faciitis.