I have a quarter size lump under my skin on my right foot . It is located in my arch almost to the center of my foot. It is painful to the touch and when walking. I am a diabetic. Also in the same foot I. Have swelling in my ankle with some redness. Randomly I am getting a stabbing pain to my ankle. I can best describe it as someone hammering a nail into it. It can happen when I am walking driving or lying down.