What Causes Tenderness In Breasts During Periods?

I´m 46 year old and starting to have some irregularities with my period, getting further apart between cycles. Usually my breasts are sore before getting my period, but lately this didn´t happen all the time, but in the last one I had, my breast were tender before but I just finished and they are still bothering me. Is this because of hormone imbalance related to perimenopause? Is it normal that my breasts are sore even after my period? Not pregnant for sure. Thanks.