Girlfriend got her period today, regular flow but some serious cramping (side effect of hormones)
I have also heard that if taken withing 24 hours the failure rate is only 5%. The 89% is a reduction rate of failure at 72 hours meaning that only 2 in 100 women will become pregnant if taken withing 72 hours. This risk is markedly decreased by taking it within 24 hours. I'm more worried about her health than anything.
I figure that the timing on her period wasn't right for pregnancy, and the discharge occurring the week after was a good sign. I'm just waiting now on her period to actually start.
Plan B can certainly cause all of the symptoms your GF has been experienced. That said, because it has a failure rate of about 25% she should take a home pregnancy test about 14 days after unprotected sex if she doesnt get her period by then.