what is this rash?!

10 week old baby boy just got this rash this morning. He was babysat last night by husband's aunt And she gave him a bath. It's also behind his ears. Could it be from maybe the soap she used? Not sure what else it could be from. He has had baby acne in the past, but he hasn't had that in a couple weeks and it wasn't this severe. He smelled very 'perfumey' when we picked him up.