Problem with my periods!?

I am 19 years old. My period begun when i was 11 and it has been normal since then. There used to be flow of slightly bigger lumps along with the usual blood. This time i had quite an unusual bleeding. It lasted for more than 15 days and the amount of blood that went out was a bit less than usual when the period lasted for no more than a week. I went through various links and learnt about Menorrhagia but it especially dealt with older women and so the cure suggested was hysterectomy. I do not know what is this.