Why does my right nipple hurt?

I'm 16, on Trinessa birth control, it's the 23rd and my period should be coming around the 1st. I haven't had sex in about two+ weeks either. I woke up and my right nipple has been hurting really badly like there's pins being jabbed into it. There's no signs of bruising or anything, it just hurts. I've looked for an answer on google and I haven't found anything. What could be causing it? My birth control? I don't think I'm pregnant because it doesn't feel like how they would feel if I were pregnant. It's just painful, and only the right nipple. Help, please?! And no, there are NO lumps or anything like that, so it's not a cyst or brest cancer. It's the tip of my nipple >.<