... pills in the first week of the pack and 3 pills during the second week and yes I had unprotected sex during those times. During the second week of pills I started to spot lighly and it got slightly heavier. I spot on and off and last night(3-18) I noticed that my breast are very tender and sore. Am I just having bleeding due to lack of hormones from the missed pills or could it possibly be implantation bleeding?(my period is not due untilthe week of 3-24)