burning foot pain

I am a 56 y/o white male.  1 year ago I began to experience pain in the ball of my feet and in my toes.  It is burning in nature.  There is intermittent redness on the ball of both feet.  Walking on a cold surface causes immediate relief.  Sitting down and elevating my feet also causes the pain to go away.  I have had a complete lower back work up including ct and mri.  there is no stenosis or discogenic problems.  Metabolic workup is likewise negative.  There is no insuling resistance, thyroid dysfunction, no hx of heavy metal exposure.  a 5mm calf biopsy shows a result value of 4.82.  Dx from the pathologist is small fiber neuopathy.  I have tried tricyclics, pregablin, cymbalta, tramadol.  None seem to offer any relief whatsoever.  I am thinking about trying either a calcium channnel blocker or a sodium channel blocker.  I am also wondering about erythromealgia as an additional differential diagnosis.  Any help you could offer would be greatly appreciated.   \
Sincerely,  Bruce Tolman D.P.M.