Could Irregular Periods Be Due To Unwanted 72 Pill?

My age is 27 yrs and I took unwanted 72 pill on 13 Dec14 my last period that I got was on 4 Dec and so according to me my next period should come by 4 Jan as per my regular period history but I got my periods on 20 dec14 and then again today on so10 jan15 I think it is bec of side effect of pill.... But my period is getting irregular bec of that so do I need to worry abt that? and plz advise when my period cycle will turn to normal?