Without examining you, I can only make suggestions. One possibility is a nerve entrapment or Tarsal Tunnel Syndrome. You might possibly have referred pain from your back (sciatica). I thought of this as the Neurontin seems to help you. You might ask your doctor or physical therapist to consider using a TENS or galvanic stimulator or an interferential unit for your pain.
I am sorry I can not be of more assistance. Good luck.