Alesse-28 and Blood Clots during Menstruation

I am 35 years old and have been taking Alesse-28 for at least 3 years. My period this month was very strange. I started bleeding before I finished taking my last active pill for the month. Then that night, I flooded very heavy. The next day I experience a lot of very large blood clots. Then I left the house and did a lot of walking during the day. During this time, I had no noticable flow at all. Once I was home, relaxing on the sofa, I could feel I was flooding again. This time again there were large blood clots. I have noticed blood clots before, but this has been unusually large. Finally today (my 4th day in) I am back to a normal blood flow. I thought that birth control pills were supposed to help minimize flow and other symptoms. Do I need to call my doctor and switch pills?

Thanks,

Bobbi