new w/ questions and concerns

hello everyone what could this be ?? last yr i had a ingrown hair right above my knee . i kept messing w/ it until i picked a really nice size hole in my leg. it finally healed but never completely , it would heal but with a blister like thing. well i left it alone for the most part for along time until recently i had bought this sulfur soap and it made the blister bust and a hair came out of it and blood and all that yuck stuff. then it will heal up and do it all over again .. i have a few spots like this from ingrown hairs that wont go away ..they heal as a blister and pop and do it all over again.. any clue ?? im going crazy trying to figure out what it could be . after the blister like thing pops there is no noticable hair there but then it does the process all over again.. i went to the doc once but she just said i was crazzy and there is no hair . well there is something makin these things not heal . help please