Strange bump on my penis

Well, im 14 years old, and I started masterbating a year ago. Now, I have this strange bump on my penis, it doesn't really bother me unless I push on it. It looks like acne almost, its been there for like 4 days. its not going away, its getting dark in color. Please Help!

I would either go and see a doctor about it...or search it on google that can usually give you some info. don't leave it to long to check out.