Thanks for the query.
In case of regular periods as she finished her periods three days before the act, there is very less possibility for ovulation at that time.
So there is very less possibility for pregnancy
As she took the emergency pill the symptoms she is having could be side effects of these pills.
For more details:http://srsree.blogspot.in/2012/08/emergency-contraceptive-pill-short-term.html
So let her wait for few more days,possibly she will get periods soon.