What Is The Treatment For Dense Breast Tissues?

hello. over the past month my right breast has become a little larger than left breat and there is like a moon shape hard section inside under nipple. it disappears when i put my arm up and then is there again when normal position. I had it checked out and the nurse saidf she couldnt feel anything suspicious but it was hormonal? It is far sorer and harder after ovulation, but only noticed it very recently, i am 36 and had 2 children and did not breast feed either. she said that breast had denser breast tissue?

thanks