Small fiber neuropathy is a symptom. When it is termed idiopathic, it means they have found no 'cause' for your SFN. Often times, SFN is related to diseases. Many people on this forum have diseases that are associated with or potentially are the causes of their SNF. Others of us, are the 'idiopathic' ones.

Idiopathic is a diagnosis arrived at when every other disease that causes SFN is ruled out. It is a diagnosis of exclusion.

I think there is a thread Neuropathy Basics or something like that. Neuropathy 101 is what it is.

You are correct to question the medication of just your neuropathy, without the docs having explored the causes. Getting to the cause may take years, and even after years of testing you may remain, 'idiopathic' for the time being.

There are conditions where neuropathy precedes the onset of other diseases by years.

Check out neuro.wustl.....I can't give you the exact web address but it come up on a search.
There are hundreds of reasons for small fiber neuropathy, and most of us feel those should be ruled out prior to calling it idiopathic.

Good luck with your searching.