I'm not going to lecture you; I know you wear sunscreen, but sometimes $h!t happens. The best way to take the burn out of a sunburn is to rub white vinegar onto the burn with a cottonball. I know it sounds crazy, but it totally works. It works even better than aloe.
The second day we were in Florida, Chuk and I both got sunburns that we didn't notice until later in the evening after we had gotten back to the condo. We applied vinegar and slept with it on. We were stinky, but we didn't hurt the next day.