Diaper change

Hello,

My 1 week 2day old baby has been pooping so much he has a diaper rash. We change it so much cause he poops so much and also put Vaseline all around. Is my baby the only one? I feel so bad not sure what else to do. I started to wash his butt under the sink instead of using wipes to see if that helps so we will see. He’s been crying and his cry seems like he is in so much pain. He did get a circumcision 3 days after he was born but it seems to be healing great. Any advice?