My period isn't due for another two weeks, and i had unprotected sex a few days ago and have started spotting very lightly but it's a dark brown ???

Wait and See: You may have had unprotected sex around your time of ovulation. This, of course, puts you at risk for pregnancy. If your cycles are regular and your next one is late, take a pregnancy test. Some are sensitive enough that they can detect pregnancy 4 days before a missed cycle. You could also do a serum test a week before your would be due. But just wait until your expected cycle and see.