What does all this mean?! help?

Well I had sex friday morning and I took the plan b pill saturday evening because the condom broke I'm supposed to ovulate today and start in two weeks but Im scared because today is Wednesday and I'm getting cramps on and off I feel nauseous even if I think about being pregnant and my lower back hurts these sound like side effects of the pill but I'm a person who worries all the time please answer me please..I need help