Sounds simply like either irritated skin from whatever protection you used, or possibly its jock itch? (which btw, is usually pretty easy to get if your all sweaty and active with.. Well.. Anythin to cause heat between your legs, jock itch usually tends to start on the scrotum and spreas out around the crotch then to the thighs, try an antifungal powder and if they grow or start getting flakey and musky smeling go to a doctor cus it might not be just that