Geez Moo has such bad nappy rash he can't sit down! He has been crying all afternoon and is too scared to walk, it must be so painful

He normally wears cloth but I want to switch to the pull up (not training) overnight as he is so hard to get nappies on. So I trialed a pull up today and he did a poo in it, since then he's had the rash.

I don't know what to do! I've tried putting cloth back on but he's still screaming, I tried nappy free but he just stands there screaming and peeing on the spot. I don't know how to help the poor kid, it's sooo red and spreads all where the nappy was.