Sayang, since baby baru 1 bulan 5 hari and the rash sudah spread kat whole body dalam 2 hari, please go back to the clinic or go to emergency , kena check properly to make sure OK je, especially at this tiny age. Better safe than sorry! A few of my mum friends, their babies pun ada similar rashes, but it's hard to tell online whether it's heat rash or something else, doctor kena lihat betul-betul, especially kalau baby asyik scratch or uncomfortable. Don't worry, most likely fine, tapi at this age better get it checked again ya.