Hi Ragtop, I happened to see this thread as I was reading through some of the recent new posts.

If my neurologist told me that I was at the point of diminishing returns regarding further testing, I would want a second opinion. Perhaps when you go in for your annual physical your PCP can order a skin biopsy for you. My PCP ordered an MRI and a doppler test for me when my neurologist didn’t think it was necessary.

Your PCP should also be able to give you a referral to another specialist. By the way, are you sure that your health insurance requires a referral? That used to be the case with my insurance, but this year my coverage changed and now I’m able to see any specialist in my geographic area without a referral, assuming the specialist herself would be willing to see me without one.