Strange Brown Discharge?

So it started off as a normal day. I got 8 hours of sleep, packed my bag for the day and hopped in the shower. After my shower, however, I had super bad cramps in my lower abdomen and sides. The cramps stayed for like 15-ish minutes then just magically disappeared. Then I went to the bathroom before my class started this afternoon and there was this weird brown discharge in my panties. Normally any discharge I have is clearish or creamy. And my last period was a couple weeks ago and I'm not supposed to have another for 2-4 weeks (I'm seeing a doctor about that next week). Any help?