Could Brown Spotting, Nausea And Fatigue Be The Symptoms Of Pregnancy?

I HAVE HAD UNPRPTECTED SEX A FEW TIMES IN THE LAST MONTH...... MY PERIOD DID NOT COME. A FEW DAYS AGO I NOTICED BROWN DISCHARGE IN THE LNING OF MY PANTIES... I THEN BEGIN TO WEAR PANTY LINERS AND THEN I BEGIN TO NOTICE LITE BLEEDING.....MEAN IT WAS BLOOD BUT NOT ALOT JUST ENOUGH FOR A PANTY LINER AND NOT A FULL PAD....COULD THIS BE A SIGN OF PREGNANCY? BECAUSE I HAVE HAD NAUSEA AND FATIGUE SO COULD I BE PREGNANT?