My periods have been slowly regulating since getting on medication with the exception of last month because I got covid and it delayed my cycle a little.

We had sex two days ago and yesterday I noticed my breast was a little tender and today it’s still tender and they are both swollen. I’ve never had breast tenderness minus when I was pregnant with my daughter but I noticed that on cycle day 28 when my period should have started. Today is only day 15 I believe. What does it mean? Should I be concerned??