Aside from saying that I would be careful about the outputs of a menstruation app (they aren't necessarily accurate), I don't know what might be causing the breast tenderness. It could just be minor fluctuations in your hormone levels.
Would you say this is a normal amount of tenderness/soreness for you at a different point in your cycle? Or does it feel out of the ordinary in general?
"In between two tall mountains there's a place they call lonesome.
Don't see why they call it lonesome.
I'm never lonesome when I go there." Connie Converse - Talkin' Like You