About a month and a half ago I took a plan b pill for the first time ever. My period after taking the pill was completely regular, not early or late. But now, a month later, I have my period again but it's a week early (while I'm still on my birth control pills, not yet on the sugar pills), and it's showing no signs of slowing down. My flow is only getting heavier every day. I'm afraid I'll have a period for two weeks. Is this normal after taking a plan b pill?