I've had my Mirena going on two months now and though I spot kind of heavy a lot, that's not what bothers me, what bothers me is that I have SEVERE cramps. like to the point that when I'm at work and a cramps hits it makes me I have to stop what I'm doing and bend over until the cramp finally subsides enough for me to continue working. How long will this last and is it normal to have cramps like this?