Vaginal Acne!

Whenever I Get My Period (& Sometimes A Few Days Before), I Get Acne On The Outside Of My Vagina... Sometimes They're Just Harmless Little Pimples But Other Times They Are Big & Painful...I Shower Once A Day, I Use Pads (Because I'm Terrified Of Tampons) But I Change Them Regularly & I Use Scentless Cleansing Wipes...Does Anyone Else Have This Problem? Does Anyone Know How To Get Rid Of Them?