I hope you can figure it out, Susannah. My skin is really sensitive and reactive, and I often have various bumps and rashes appearing, sometimes to be gone an hour later. Others last, and I've had to use eczema cream for those. Or taken an allergy med, like Benadryl or Zyrtec. Is it possible they're some sort of allergic reaction? You could try taking an oral allergy med to see if that helps. And, possible gross warning, do they have white dots in the middle like pimples can get sometimes? If so, they could be staph (not necessarily MRSA)--I ended up with that on my leg a few years ago and had to take antibiotics. Those were rather painful though. I'd get another opinion if they don't go away or start getting better in next day or so. Doesn't sound like shingles though (I thought that was what was going on when I had staph, but it wasn't the right pattern).