Uterus from Hell

So ever since I started my period at age 13 I have experienced severe cramps within the first 2 days of my cycle. In fact, they are so bad that I have fainted on multiple occasions (my friends literally call me the "fainting goat") and I even got a concussion a couple months ago because of it. I recently had Mirena (IUD) inserted in hopes that it would help regulate everything and keep me from fainting for the next five years. Unfortunately, it's been a little over a week and I have not gone a day without some sort of cramps/spotting. I'm going back to my doctor for a follow up soon, but I was wondering if anyone else had experienced this. Is there any hope for me? Am I the only one with a uterus from hell? Help.