I'm 16, with an uncircumcised penis, and I masturbate daily. Over a few weeks, I've had this boil towards the base of my penis. It seemed to have subsided, but recently after I masturbated, I found a sharp sensation at that spot, and on checking, I found that it had begun swelling again, and it seemed like the remains of a discharge were present at the edge of the boil.
Please note: There is another less severe boil towards the top, but it doesn't cause any pain.
If it doesn't go away and you're worried about it, you could see your doctor, or if you're in the UK, you could go to a genitourinary medicine (GUM) clinic - google "GUM clinic near me" for details.
I that that masturbating every day is normal at that age btw.
If you're in the UK, you can see a doctor or go to a GUM clinic without your parents finding out - they're not allowed to tell your parents without your permission, and if it's a GUM clinic, they don't even need to know your real name. If you're somewhere else, try googling "seeing a doctor without parents knowing".
There's a very good chance it will just fix itself though. You could also try googling "boil on penile shaft".
First, congratulations. You've already won one contest! Secondly, I'm going to presume that you have not had sex with another person, and frankly, it does not look like any STD I'm aware of.
That being the case, please don't be embarrassed about bringing it up to your parents. I went running to the doctor once thinking I had contracted some sort of STD... it was red, ugly and had a puss head. He was able not to laugh at me when he lanced an ingrown hair.
So make the appointment, tell your parents you have something like an ingrown hair that may have become infected or something... plead ignorance, but insist on seeing a doc because if there is one thing a 16 year old boy doesn't want any problems with, it's his junk!
It will be easy with the doc... he's used to it. And the bottom line is that no matter what... even if it's some kind of bad news, you must have it examined by a doctor. Even it it's bad news, you will get over it... just get it fixed and resolve the matter.