I had PUPPP during my pregnancy too. maybe because I went to government hospital and I don't have like a fixed gynae so when I tell them about my rash they also can't give me an answer or solution. I read that it will go away after giving birth but it got worse right after I gave birth and I was referred to national skin center. they gave me steroid cream, medicine (which cause me to cannot breastfeed) and use Cetaphil gentle skin cleanser. but most importantly must not scratch them as it will cause them to spread. when it itch try to use ice packs to soothe and keep yourself dry and cool. I also read somewhere that this rash is caused when we never take enough nutrients while pregnant.
Better consult with a dermatologist to give you medications that is safe throughout pregnancy.