No idea at all what it is but
Don't listen to those scratch-o-phobics , no ,
just scratch the living fuck out of it , teach it a lesson , it will make you feel better and helps get the crap out , especially those pustules, as long as you keep it spotless clean afterwards.
maybe get some anti histamine tablets (not creme ), the ones that DO make you drowsy are best, and take in early evening .
Don't look like prickly heat , but the powder might help anyway .
if it's not better soon ask the pharmacist in Boots or see a doctor .
get well soon mate .