Thanks for the query.
Emergency pill can cause menstrual disturbances like altering the period of menstruation
and also they can cause inter-menstrual spotting.
For more details:http://srsree.blogspot.in/2012/08/emergency-contraceptive-pill-short-term.html
Possibly this spotting will subside soon and you will resume your cycles.
Usually bleeding will stop after around 4 weeks from delivery.
Better to avoid emergency pills and choose some regular method of contraception
like barrier method or progesterone
pills to avoid future problems.