Please help! Does anyone have any idea what this rash could be?

So a couple of days ago my 7 month old baby had just a couple little bumps on her belly I thought maybe it was just a little heat rash she had a fever a couple days before I noticed the rash. but then this morning it spreaded it is all over her tummy back and privates. But I really have no idea what it is? Does anyone have any idea?