Question about plan b

So I know that breast tenderness is a side effect. I took plan b about a week ago(my first time ever taking it) and my breast tenderness is still present. I also know that it messes up your cycle severely and I have not gotten my period yet. So I was wondering if that is causing the breast tenderness to linger. I have had mild cramps, but that's pretty much it.just wondering Did/does anyone have similar expierences? I'm all kinda nervous about it all and just wanted to chat about it a little bit to ease my mind.