Oh my, I wish I could help you with that. But I checked pictures and it actually looks like worse version of what my 4yo had on his butt recently. It spreaded quite quickly, rough to the touch and then started turning red. After few unsuccessful attempts with zinc creme and whatever, I started using propolis in alcohol, bought small flask not long before. He was unhappy, said it burns, although it looked dry with no open skin. It helped for that within two weeks. Try it, but that alcohol is savage on skin.

If you wanted I can buy it tomorrow, I'm currently next to the beekeeper I'm buying all this stuff from.