for the past 4-5 months my breast have been getting sore one week prior to my period with more pain in my left breast. it is 2 weeks untill my next period and i have pain mainley in my left breast and after feeling them i feel more hard tissue in my left obreast and it is larger then my right, which it has been my whole life but ive never noticed this difference in tissue or the tenderness. i am a 26 yr old female. any idea of what this could be?