Reaction to acupuncture

Some people do have reactions like this to the needling. In my personal experience it is very rare, but I imagine it may happen more with other needles/techniques. You've already ruled out the usual suspects to some degree. Acupuncture needles are sterilized, so some people have a mild allergic reaction to the sterilization agent used on the needles. Some needles also have coatings on them for smoother insertion and occasionally people react to this as well. If you are reacting all over and have had multiple brands of needles used you are most likely reacting to the sterilization agent used on the needles, which is common amongst most except for those with coatings like Seirin needles. Have you had a practitioner try Seirin needles on you (they are the japanese style needles, with the colored handles)? Out of all the needle brands, these would be the ones that are least likely to react.

The other cause is the needling technique used. Needling too shallow may cause a reaction of this kind on people with more sensitive skin. If you are seeing many practitioners of the same style, this may be common amongst them as well and you may be reacting to the technique more than anything else.

So it sounds like most practitioners have said about the same thing - you are probably allergic to the sterilization agent on the needles. So long as the spots go away reasonably soon after the treatment and you are not having any systemic allergic reactions, I wouldn't worry about it.