Biking Underwear

How do I remove stains in my butt?
I have goose bumps at the bottom of my ass. I also have problems with spots and red spots. I bike a lot and I think the sweaty underwear could be the culprit. How do I fix this problem? I sweat a lot in hot weather, how can I care for my skin there so my boyfriend will be surprised?
eww ninth suppose to look there anyway its well why u not put up ur but lol j / k
Sexy Blonde Woman Biker with no underwear on!