Rash on my new born babys face

My baby boy isn’t even 2 weeks old yet and since yesterday morning he has had a rash on his face and today it seems to have spread- he was outside for the first time the day before yesterday for a little while- could this be heat rash? Spoke to midwife yesterday who said so long as they are too yellow/pussy and he doesn’t have a temp it is probably just a rash babies get from their skin getting used to the world. Anyone else’s baby had this? I can’t help but worry... he has no fever and I have done the glass test and all fine