Not sure I understand. This sounds like you have one growth, probably a sweat cyst based on where it is and how you describe it. But you say it's a rash, but a rash would be a series of things, not just one discrete growth. Hard to know how to respond in such case.
I agree with Paxiled. Since it's recurring, you should let your doctor sort it out. Lots of things cause bumps and rashes in the genital area, so it's hard for us to narrow it down. It doesn't sound like an STD, if that's your concern, but it does sound like something your doctor should see.