Diaper rash

So I was out and about the other day and completely forgot my sons diaper bag so I swung by Walgreens and picked up some diapers. I always use the parents choice from Walmart so I just bought the Walgreens brand diapers and wipes and i have been using them just got get rid of them, but today I have notice my sons butt and testies are completely red and he cries every time he sits down. It has only been three days since I bought them and it’s bad. So of course I switched back to his normal diapers right away but is there anything I can put on it to help it heal faster? I feel like such a bad mom right now 😩