Emotional side effects of taking Plan B emergency contraceptive?

my girl got those plan b pills and took them after unprotected last weekend. couple days latershe got a real lite period lasted 3 days. shes also been a flippin head case and im startin to worry. she was cooking dinner and out of nwhere she fell on the floor sobbing histerically and she didn't know why . i looked up the site for plan b and they didnt' even list mood swings as a symtom. does this mean the emotional rollercoaster could be from pregnancy? i pulled out AND she took those pills the right way the very next morning. Has anyone else experienced/witnessed such intense emotional side affects from plan b pills?