YoungSFN - you are not alone in the being young thing - I am 22 and had my first symptoms at 19. I would say my symptoms are more sporadic and mild compared to many of the people on this forum but even so my doc has diagnosed as SFN. I would def. keep pushing for the skin biopsy - mine did not come back entirely abnormal but did have significant reduction is sweat gland nerve fiber density which led to a QSART test which showed similar results. Hope you can find your answers - not knowing can be so hard.