Why did I get my period so early?

I just got my period almost 2 weeks early. Its unusual because I'm on birth control so I'm always really regular. I'm on Nuvaring so its not like I started because I missed taking a pill and I know its not breakthrough bleeding from pregnancy because I haven't had at all since my last period. The weirdest part is that last night I had a dream that I got my period. I don't really think that my dreams are controlling my reproductive system, but I can't figure out why I started so early. Any ideas?