Hi Mat, I'm glad that you finally got a positive test results and hope it would lead to an effective treatment!

Regarding Rituximab and getting immunological treatments too late, well, my problems started two decades ago and it seemed as seronegative Sjogren, I've got POTS and other autonomic problems, the skin biopsy for SFN showed severe damage, my symptoms are mainly reduced sensation and numbness.
And I was also allergic to Plaquenil and Imuran.
After the SFN diagnosis my neuro recommended on IVIG but the HMO refused to fund it and approved Rituximab. I got the first infusions on Nov, and repeated it recently.
Although my POTS and SFN started years ago the Rituximab helped! The effect on the POTS was significant, my standing HR dropped from ~110-140 to ~70-90! My brain fog disappeared, and I had a lot more energy.
It is harder for me to estimate the effect on the SFN (I had a traumatic skin biopsy and refuse to repeat it), but it seems there have been less burning, tingling, numbness, my feet got warmer so the blood circulation probably improved, and I feel the perception of temperature in my hands improved.
It took about 2 months till the improvement started and it lasted about 2-3 months.