Late period

I had posted anonymously, but I just figured it wasn't fair. I was supposed to get my period yesterday.... Still didn't get it at all today....until I felt light cramping....so I went to the bathroom and noticed a very small ammount of dark brown discharge in my underwear. I had out in a tampon, took it out like a couple of minutes after (probably not healthy) and there was a little bit of dark brown discharge still. I'm kind of concerned because normally my periods don't come late, and they're always heavy....and well, not brown. Any help would be appreciated!