It could be implantation bleeding, if you've been having unprotected sex, even if the man didn't ejaculate, there's always pre ejaculate which does contain sperm, and there is a chance of pregnancy, wait and see if you are late/miss your period and take a test if you do. Good luck!
i found out i was pregnant by brown spotting... i thought it was strange.. googled it.. found "implantation bleeding"... took the test.. and ta dah.. i was pregnant! Go buy a cheapy test at first and check it out just to make sure you are or arent and wait a few more days! P.S. i am spotting throughout my whole first 2 months so brown spotting is def. a sign of pregnancy!