Period Blues for week in advance?

Hey! So I was wondering if anyone experienced problems a week leading up to your period after taking Plan B in the same month. It's been a few weeks, and I spotted after taking it, and now I'm expecting my period in 5 days (fingers crossed) and I've had acne, nausea, backache, headache and cramps all leading up to this thing for the past week. Is that pretty normal or should I be concerned? My uterus feels like it weighs 5 pounds today and I haven't done much but sit around and cramp on and off. Thank you!