Plan B issues

Took two pills last month. I should have had my period 12 days ago. Does Plan B throw off periods this far off when you take it twice in a month? It was my first time to consume these pills. I took a pregnancy test last week, and came out negative. I will try again once another week passes by. I have also been feeling a hard stomach on my lower abdominals, and cramps, I did have a period of days where I just wanted to eat and felt gross afterwards. I felt bloated, and working out didn't feel. after a few days, I don't feel as bloated. However, the side effects that have not been gone is that hard feeling on my lower abs, I got a back adjustment with a chiropractor two days ago, and it hurt me a little bit in that lower area when she applied pressure. I don't know if Plan B side effects last this long because it was my first time taking it, plus I took it twice in the month. Has anyone had this problem?