Boobie/nipple talk TMI

Slightly embarrassing but I suppose where all ladies here🙈 need your opinions!

Basically since as long as I can remember probably ever since I grew a pair of boobs, on my right nipple, right in the centre it’s like very dark almost purple dark brown crust.. I’ve never had any children.. yet lol & I got my period when I was 11.. I remember having it since the start of puberty. Anyways I tried picking it off when I was like 15 and underneath was just loads of like pusey yellow stuff which wouldn’t come out, I went to the doctors about it and they said to just leave it alone and I will grow out of it.. 3 years later I’m now 18 and I still have it I’ve just left it not touched it like the doctor said but it’s still there! So the other night I picked it again trying to get it off it’s almost like a scab that won’t come off! And I know picking it is probably the worse thing to do but it won’t budge. And as of now it’s just like a yellow scab crust thing on the centre of my nipple, I’m really fed up and embarrassed of it because when I go to have sex I don’t want my partner to see! He has asked me before what it is and I just lied and said hormones because I was to embarrassed to say I didn’t know what it was.😫 help😩