Hardness Under Right Nipple.

Ok, now the first thing you are already thinking is puberty or something of the sort like hormones. But when i was around 12-13 I first noticed this hardness under my right nipple and as I got older it got bigger and I also noticed that there was also one forming under my left nipple too. Now I was under the impression that it was puberty and I still believe that today. What I don't understand is that the hardness under my right nipple went away and I only had the hardness under my left nipple. Then, after a while I decided to let it alone and before I knew it the hardness would be gone. It was gone but the weird thing was that the hardness in my right nipple was back and even bigger than any other time. I'm 20 years old and had it for about a year now. Maybe longer. I can't be sure, but it's about as round as a quarter and feels thicker than a my finger. It hurts a little bit when I feel for it. The other ones when I was younger hurt when I felt for them too. My cousin is a nurse and told me that it's good that it hurts because cancer doesn't hurt. I still want to know what it is and if it will ever be gone because it's very annoying and it makes my nipple stick out farther than the other one. My right nipple is also slightly bigger than my left too. Directly under my right nipple where the hardness is it comes to a rounded point. Almost as if it is forming in the shape of my nipple. Anything would help. Thanks.