I had 4 pills left in my pills n started having brown discharge, it lasted 5 days then had my period for 2 days, it stopped suddenly, could I be preg?

Possibly. From what you describe it's possible you are pregnant but unlikely if you were taking your birth control pills as you are supposed to. It's more likely that you just had brown discharge because of a light menstrual period. If you are concerned then do a home pregnancy test.