My daughters face looked just like that, turned out she had excema. had to switch all her clothes and toys to 100% cotton. As well as detergent's. It can be a heat rash just let it air off for a few hours.
Could be heat rash or irritation from detergent...definitely do the breast milk thing! I swear that stuff cures everything lol...if not nursing try coconut oil instead, like breast milk it has anti fungal and antibacterial properties to it 😄