Pregnancy could be a possibility have you taken a test? Maybe your hormones are out of balance. I'm not sure what it could be so maybe you will need to go to the doctor to figure things out if it continues. Best wishes BB
Benign breast disease usually causes severe tenderness in the breast. I'm a nursing student and have memorized issues of women's health.
The breasts will feel tender almost always but especially during your period. You made feel small "nody" circles in your breast. More than 50% of women will have this disease. It is not cancer or serious. The only risk it carries is that the nodules may conceal a true concern of a tumor in the future.
Breast tenderness is not always a 'sign'of pregnancy. I suggest seeing a doctor about not having a menstrual cycle in almost a year and now experiencing tenderness.
Good Luck
the only thing i can think of is that u could b prego . because tenderness in the boobs is one of the first signs of pregnancy. So maybe u should take a test that way u can rule out that possibility.