On Jan. 31st, I took the Plan B pill and had a normal, on time period that month. But this month I've had a constant dull pain in my lower left side and I started spotting yesterday. Of course, I freaked out because I've never had anything like that happen to me before. Today I woke up with a full on period, but I'm not supposed to start for another 10 days. Usually I'm exactly on time, if not a little late. Is that a normal, okay thing to do?