possibly TMI but please help

the past couple of days my left boob has been really quite sore. especially my nipple.

so i was having a look (as you do) and i saw that there was this white yellowish thick stuff sticking out of my nipple so i kind of rubbed it off i suppose and it really hurt to come out and now there's like a red/browny dot in my nipple

does anyone know what this is?? i'm really sorry if this is tmi i'm just a bit freaked out 

also i'm 16 and a virgin if this affects anything