What Causes Prolonged Periods?

I went off the birth control pill 3 months ago and my first period was normal , but this month I on my third week of my period , I am 51 and and have been on the pill most of my life for that reason. my periods are heavy and lengthy and have been for the last two years , I went off the pill thinking I just may stop all together but no luck so far, hoping for relief soon , thank you