Hi everybody
So here is an update of my situation!

I have been seeing a well-known doctor that is specialized in SFN and Sjogren's. He offered me to take me to the hospital for three days in order to have extensive tests done. I was at the hospital last week.

And... NOTHING came back from it.
I did not expect to have an underlying cause identified, but at least I thought they would confirm SFN for sure... but they did not.
I did not have a skin punch biopsy (even if I asked for it), as they told me it would be useless, as all my small nerves were functionning just fine. The test I underwent is called Laser Evoked Potentials and came back normal -which, for them, means that my small nerves are all there-.
To conclude, the doctor said that it might be an early stage of SFN, with hyperexcitability. He explained that before dying, small nerves are first hyperexcitable.

Coming to an underlying cause, they ruled out the Lyme (haha, what a surprise). Even though I have a confirmed first stage of the disease, the tests they performed at the hospital (blood and from lumbar puncture) all came back negative in Igm and Igg. I was blown when a neurologist I saw told me that "Lyme is simple to treat, you had the antibiotics blabla and even if you still have it now, this is too late to do anything..." Incredible
I tried to mention an auto immune driven reaction (as it all started Guillain Barre style), but they did not go further on that.
I don't have any underlying cause identified so far. I don't have autonomic symptoms.

I felt like it was the greatest SFN spectialist in France and here it is...

I am now so scared. He is seing me back in 3 months and offered nothing but Lyrica.
I am 26 and life does not feel the same anymore. I live with the pain and the fear of the disease. I am scared about my future, and it is getting hard for my girlfriend, family and friends to see me like that. I see all my friends traveling, getting married and having babies, and I feel like I can't do that at the moment, which is very depressing.

I have read somewhere a post by en_bloc explaining that skin biopsy can show not only loss of fibers but also damage. I don't know yet if I will be able to have a skin biopsy shortly.

So now I will look for a LLMD as you guys suggested, however it is going to be hard.
Madisongrrrl, your doc thinks that your SFN is immune mediated and not caused by the Lyme itself (or co infection), am I right? So what can be done to stop this process?

I also want to start supplements, I need to read about that.

Thank you for reading ! All the best to you all.