Diaper rash 😭

I’m so upset my 1 week old has a diaper rash. His little butt is all red and bumpy and idk how it managed to even do that. The only time I don’t change him immediately is when we are sleeping because he doesn’t wake up mad about it. But he wakes up normally every 3 hours and I change his diaper after feeding. I just hate that he’s probably in pain. I’ve been using butt paste on him (noticed the rash yesterday). Is that a good ointment to use or does anyone have any suggestions of something that works better? Tia