The NHS does have strict criteria for use of IVIG, but this positive lip biopsy should open the door for you. Have they already told you that you won't get IVIG (after you have the new lip biopsy results)?? If so ,what is there reasoning?

Yes, I have also used Cellcept. It was helpful for some of the neuropathy symptoms and pain. However, I got a life-threatening infection and had to stop taking it. I have an immune deficiency, so this complicated my situation. Most people do just fine with Cellcept...so don't let my experience keep you from trying it.

I have not tried Enbrel, so have nothing I can add about this treatment.

Don't let the 'sero-negative' label keep you from getting proper treatment. Your lip biopsy just changed the outlook of that label. The lip biopsy is the gold standard for diagnosis...so holds a lot more weight than a blood test.