plan b problems!

alright, let me summarize this. i have anxiety, first off. so birth control is important to me. i was on it, recently got off bc i ran out and had no way of getting refills. so we've been using condoms. well, just got off my period. a day later, had sex, had a problem and had to take the plan b pill. ive take it twice before. it has been less than a week, i just started to get cramps and the blood is CLOTS. like i know thats tmi but i normally rarely have them and now i have allot of them. what is happening?