Can Crisanta Cause Prolonged Periods?

I have minor PCOS problem. My periods were regular.I am suffering from acne since 7-8 years now. My dermatologist prescribed Crisanta LS to me. i have started having the pill from the 2nd day of my periods. Usually my periods last only 3 days. This time im still getting little blood flow on my 4th day as well. I am scared if the periods will be prolonged and will continue to have the blood flow for more no. of days. Can this happen? Also, can i get spotting persistently during the course of having this oral contraceptive?