Rash help

My 5 month old has a yeast infection drool rash on his neck that we got prescribed cream for. He had this redness on his tummy when we went in and she didn’t say anything about it when she saw it. And on his back. Idk if this could be a side effect from that infection if that’s even a thing? Or if maybe it’s eczema but seems like a lot to be that? He has eczema in the typical places already like creases. Or maybe it’s dermatitis? It wasn’t our typical doctor that we saw so I feel a little on edge about it even after going in. Would you get a second opinion or trust & wait it out?

I’ve been putting on aquaphor & aveeno lotion we’ve always used.