Thanks for the query.
The scanty flow during periods and pain abdomen can be due to the emergency pill you took.
Emergency pill can alter menstrual cycle and repeated use can also lead to some short term and long term side effects.
For more details:http://srsree.blogspot.in/2012/08/emergency-contraceptive-pill-short-term.html
As you took the pill within 72 hours possibly it will give protection and the chances of pregnancy
But if you miss the next expected date of periods better to get examined for pregnancy once.