In the last three weeks, multiple bumps almost like bug bites have broken out on my inner butt cheek and I was wondering what it could possibly be. Around the time I noticed the rash, I had just gotten back from a camping trip where we had gone swimming in a pond full of algae. I didn't take off my bathing suit for almost 7 hours. Some bumps have healed, I've scratched some until they've bled, but they seem to recur sometimes.