Hi I am 23 year old male In the middle of my waist there is a painful bump it is white in color it is 3 inches below my belly button. It is only painful when pressure from my waist band is in contact with it thought. This is not the first time this has happened. This bump has appeared two other times when I was younger but before I could get to the doctor it would pop the doctor would always tell me there is nothing they can do after it has popped. When it pops white fluid/tissue would come out and start to bleed. After a week or so it would turn into a little black dot, I still have both black dots on my waist from the previous two times this has happened. Each time it has come back an inch or half an inch higher than the last time always a year or more later. I get tested for every sexually transmitted disease regularly (every 6 months) and always came back negative. This time it appeared 2 or 3 days ago and today it popped when i was getting undressed a small white tissue of some kind sprayed out of it followed by blood. I do not know what to do and always seems to be gone before I can go to the doctor. Any advice would be greatly appreciated. Thank you