How should i be treating this?

Help please my 2 year old is fully potty trained except for naps and night time. She had a poopy diaper over night and didnt tell us/ cry for us, so we had no idea. She has a roarin diaper rash, and it HURTS her. I feel so awful for her. Its beginning to look raised and polka dotty to me. Ive been lathering her in aquaphor/ buttpaste when she goes to bed, but this is day 3. Keep using diaper cream or treat it as a yeast infection?