Is this is it like a skin yeast rash Ive heard babies can get those? Is it from drooling or being wet or what?? (He drools sooooo much) or is this Dryness someone help! What can I use?

I gave him a bath dried really well and put eucerin baby lotion( it’s what I have in hand) he’s now sleeping I will see how he wakes up. I’ll probably call his ped but being Friday tomorrow most likely they won’t see him till next week any suggestions of what I can do