I've had four (or maybe 5?) during my lifetime. Two prior to developing CRPS, and two (or three) after.

The only truly bad experience was the last and it was several years into the disorder. My doc had advised against it,since it is considered invasive for CRPS patients, but a WC doc had ordered it, so I felt I didn't have much choice. The technician didn't attempt to finish because she felt it was cruel. I was silently crying, but she could tell I was in agony. I was unsafe to drive after for a few hours. I immediately applied one or two Lidoderm patches and took additional pain meds.

If there is a real chance of it being a different nerve issue, it's probably worth trying. I have to say though, a risk I'd be willing to take for myself--causing potential spread or an exacerbation of symptoms, I wouldn't have considered for my son.

I would encourage you to find a CRPS specialist. A doc whose entire practice is devoted to CRPS patients or someone that comes highly recommended a CRPS support group.