What Causes Prolonged Bleeding After Taking MTP Pills?

hello sir i am from india i am taking mtp pills on 25th januaray 2012 first dose ,then second dose on 27th and third dose on 28 th jan. than after i have started for da9th to 10 th days. my bleeding is stop on 4th feb . but after 6 days today it is started again plase help me and tell there is any problem or it is in procedures and please tell me when my regular periods start. thanks pragati