The 'skin test' is an epidermal nerve fiber biopsy, taken at 4 sites, the foot near the ankle, the calf near the knee, the inner thigh and the inner fore arm near the elbow. It is taken by punch biopsy after a small amount of local anesthesia is injected. They do bleed for a few days as you have a small hole about the size of an 'emoticon' and about one fourth inch deep, perhaps more, depending on who does it. It is an in office procedure, however, will likely need to be sent to a major medical center neurology department for interpretation and it can take up to 6 weeks to get results.

You will likely have better luck with a physician referral to a major medical center. See if you can get one of your doctors to call a research facility. Waiting lists are very long.