Sun burn help. i don't know what to do. its peeling and my skin under is lighter then my tan?

so i got sunburned and it turned into a really nice tan.. but now its starting to peel and it looks weird because the skin under is lighter then my tan. i have to go out tomorrow and its going to be 90. should i wear a shirt to be safe or would it be ok to wear a tank top and put sunblock on every 20 min?