My son is 7 weeks old. The last time we visited the doctor which was about 2 wks ago, she mentioned that because of hormones my son's breasts were a little on the big side, but said this was normal and would flatten out in time. Today I notice that that when I touch his right nipple, I feel something lumpy underneath, say the size of 2 quarters. Does anyone know what this could be? Should I be worried?