Tonight as I was getting ready for bed, I noticed a sharp pain in my left nipple as I was taking my shirt and bra off. Looking at the nipple, there is a white swollen gland(maybe? I don't know what it's called, but it's those individual dots that make up the nipple) in the middle standing out father than the rest. I also started my period today if that helps with your search. I've never had problems nor any pain with breasts or nipples before so it's a little concerning to me.