ladies please hellp

So last Saturday (April 29th) I had a one night stand with a good friend I know huge mistake! Then Sunday (April 30th) we had morning sex but he never even finished. Monday (may 1st) I started bleeding it was super light tho. And dark. And I'm still bleeding today (Tuesday may 9th) I'm starting to worry. We did use protection. And I do plan on taking a test this weekend. But should I be worried??! My friends are saying it's just my period but I've never had a period like this..