Hi Yu Ping,
Has your doctor suggested a skin biopsy to diagnose small fiber neuropathy? It isn't a bad test to go through and may give you the answer you are looking for. I am also curious whether you have had an EMG/NCS as echoes posted. If your doctor has not done this testing, I would suggest you request he order them.

It sounds like you are reluctant to take medications and I agree. It is a difficult decision to make. I just hope you are not suffering needlessly when there out some treatments out there that may help alleviate some of your pain.

Hang in there it took most of us a few years to get our diagnosis.

Hopeful