Plan B and Spotting

Last week I had unprotected sex.  He didn't ejaculate, but I decided to go take Plan B anyways.  Now, a week later, I have what I guess would be considered spotting.  It's a dark brown color like old blood or something.  This has never happened to me before.  I'm due to get my period dec. 7th.  I read that Plan B can cause this.  Has this happened to anyone else?  What should I do?

[John Kim, M.D.]

Yes, this could be from Plan B. If you do not get a period Dec. 7th have your doctor check a blood pregnancy test.