What Causes Light Menstrual Bleeding After Having Primolut N?

ya sure i m 30 yrs old woman. married. no children. i have very normal regular periods each month which lasts for about 5-6 days. with little cramping on the first two days, this month...each month i get it around 19-20th...this month .this month i took primolut n and delayed my period for one day..when my period startrted i had less blood flow compared to my normal periods...and it stopped on day 4...but today i m on 6th day...and i am bleeding again...passing clots..but no pain at all.this has never happened before....i am worried....i have aenemia