Is Reddish-brown Discharge After Taking Emergency Contraception And Finishing My Period A Cause For Concern?

I am 21 years old. I had an unprotected sex last dec 28 and it is also the same day my period start. I took a 1 contraceptive pill everyday for 7 days since dec 28. I stopped taking the pill last january 3 and my period is finished too. January 6 i experienced reddish brown discharge it is not that mny to fill a pad but still I am worried. What could be poaaibly wrong with me.