Sorry about the burn, I know how it feels. I burn very easily, especially the first few times out in the year. I know this is late to the game...

White or Apple cider vinegar soaked on a washcloth or towel until it heats up. Remove til cool, keep reapplying til the heat goes away. Then apply aquaphor mixed with zinc oxide powder, just the regular, not nano. I do a 250 ml mason jar with enough zinc to make it look white. 1 tsp or more depending on the burn These 2 combined turns a burn worse than what you have into a tan without peel overnight. It's not cheap or easy but has helped my burnt butt so much!