What Could Prolonged On And Off Bleeding Post Intake Of Morning After Pill Indicate?

I took the morning after pill on the 11th day of my cycle. I started spotting on the 20th day of my cycle which varied in flow and color since. I m now on the fifth day of another cycle. I have always had a normal cycle of 28 days, however for about four months now my cycle varied from 22 to 26 days. Should I be worried or wait until the end of this cycle? I m a bit concerned because I have been bleeding on and off for 13 days now.