Under neck chafing!!

So our poor daughter has had a huge issue with chafing under her,

as we call it (no neck). Poor thing is so chubby she has no neck and when she spits up and just drools its gets wet under her neck and is getting red and and clearly irritated. I asked her doctor what I should do and she pretty much said keep a bib on her at all times other than when sleeping and keep it as dry as possible and I could use diaper rash cream on it. Does anybody else have this problem with their baby? I feel so bad.