Well normally my breasts used to get sore a week before my period, and would decrease in tenderness once my period was a day or two away. The day of my period, I didnt' have no more tenderness.
But this time around, my breasts got sore a week and a 1/2 before I was expecting my period, and the day before my period was suppose to come, they were more sore than ever. They got huge too. I couldnt' sleep on my belly like I normally do, so the day after my period was supposed to come, I took a pregnancy test, and it was .
I hope this helped. Best of luck with you friend.