What Causes Prolonged Menstrual Bleeding?

Hello Doctor,I am 36. For the last two cycles my menses have been very scanty . The first one that came on May 2nd lasted till May 9th with very less bleeding, practically can be called spotting. I got my next cycle on 30th May as per schedule and again there was spotting lasting only 4 days. I checked with my gynaec and got all my tests done including sonography of pelvis and thyroid. Sonography of pelvis showed one single very small fibroid (doc said not to worry), a simple cyst in the rt. ovary ( doc said this was normal and not to worry), Endometrial lining was 11 mm. Thyroid, CBC, Urine and Sr. Creatinie reports were normal. But, I again got my periods on 11th of June and the bleeding still continues and I need to take atleast 3 pads a day. Small clots are also passing. My gynaec gave me CLIP 500 3 times a day to be taken for 3 days. Request you to please advise if there is anything to worry about or if this will go back to normal.