bumps in pubic area oozing blood.

there is a round bump in my pubic area, its not painful but irritating when touched. when it blisters pus comes out followed by blood, it dries up within a week. usually only one appears at a time although sometimes small non pus filled appear with the one. the area it appears in loses hair so there is like a bald patch in that area. the first one came long before i was sexually active so i know it's non sexual. I also noticed it appears only when i miss a bath. if i don't bath in a day it comes by the next day or two whether i bath or not.I would have gone and seen my doc but it goes within a week and there is barly any sign that it was even there. (if i don't miss a bath)the obvious solution would be not to miss a bath at all but i am still curious as what it is and what causes it exacly.