It's been about a year since I took birth control pill, and I just got back on and finished my first week. I was given a Plan B at my appointment, and did miss a pill this week (gotta get back into the routine of things again.) I got my period as expected, about a week ago. Now, the left side of my left breast is tender and painful. Is this normal for someone who is just starting up birth control? Could it be hormone fluctuations?