Prickly heat, if you have never suffered from it, can be quite unnerving. In my case it felt like sudden attacks by invisible mosquitos. Since at the moment I found myself in the Tropics, I was more than ready to believe that there were nearly invisible insects attacking my neck. Or, faut de mieux, that I had a horrible nerve disease that manifested itself by the individual explosion of faulty pain neurons.

It is also worth noting that the blisters can also be invisible or very hard to see.

The advice given by Modern Angel is all good. See also hyperhidrosis.