Is this just a really dark birthmark? or a mole? I don't even knooow,lol.?

If it were a mole, well, it's never been bumpy or raised or whatever. But if it were a birthmark, birthmark's can be a dark brown ,right? I've had this since i was little, but as i grow older it also grows. I have a birthmark already on my back which is just a tad darker than my skin, but it's still not noticeable. however, whatever my birthmark-mole, is on the underside of my head?if that makes any sense? LOL. its the size of a pencil eraser on a pencil by now. and i'm just wondering what it really is. i know people judge me for it, and it really does bother me when i was in middle school, but i'm in high school now and i just wanna be mature about it. i cringe when my friends laugh about people having moles and i'm right there. i get all self-conscious.