constant spotting???(might be tmi lol)

Okay so I got my iud(mirena) put in maybe about 7 weeks ago, & I am still spotting. my doctor told me it was normal for the first few weeks, but it still hasn't gotten better. the discharge is very dark, almost Brown (sorry if it's tmi) & only sometimes looks redish. I also cramp occasionally, and usually right after feel discharge. Did anyone else have this problem? if so how long did it last? I want to go see a doctor but I'm currently moving states so everything has been so hectic. Thanks girlies!