"last month i took a plan b pill about 12 hours after my accident. and i got my period a week early. i did have bad cramps, but the flow was normal. this month my period is about 8 days late. i have really tender breasts, and i get cramps on and off all day. if i am pregnant it&#039;s not because plan b failed. i read other forums and people were saying that their second period after plan b was either later or didn&#039;t come."