How To Cure A Pus Filled Open Sore I My Vaginal Area?

I am 24 years old, 5'4", 125 lbs, on Yaz for birth control and had rheumatic fever as a child, the other day I shave my vaginal area and knicked myself near my vaginal opening, after a couple of days it turned into an ingrown hair, I shaved again, knicking the ingrown hair and now it has turned into a 3mm long open sore with a yellowish fluid covering the top, how can I ease the pain or help it heal faster?