I had sex 4 nights ago and took plan b three nights ago. i am still experiencing lower abdominal cramping and lower back pain. is this normal?

Probably: Abdominal cramping is one of the well-known side-effects of Plan B. Take it easy for a few days. If things haven't subsided by then, go see your doc. Hope you feel better soon!

Can be normal.: Potential side effects w emergency contraception include: menstrual flow changes (spotting, bleeding, early or late period), nausea, vomiting, dizziness, fatigue, headache, breast tenderness & abdominal pain or cramps. Take pregnancy test & notify dr if your period is 7 or > days late.