Sore breast.

I've been having sore breast and my nipples feeling werid. I got my period Jan. 2nd and on Jan. 21st but spotting very light i didnt need a pad just paper towels. I have irregular periods.

My boobs been sorry for almost a week.

What can this be?

Forgot to mention I did do a work out for the boobs but it wasn't too much and that was a week ago. I wonder if im sore cuz of that. But its werid that it's been a week. Plus I don't think my nipples would hurt bcuz of the workout.