What Causes Foul Odor From Vagina After Having Periods?

I AM 41, FOR ABOUT 2 YEARS I HAVE HAD A HORRIBLE FOUL ODOR AFTER MY PERIOD. I HAVE A REGULAR PERIOD FOR 5 TO 7 DAYS, THEN THE NEXT 10 TO 15 DAYS I HAVE A BROWN DISCHARGE THAT SMELLS AWFUL. I BATHE DAILY, BUT CAN SMELL IT ALL THE TIME,EVEN AT WORK. IT IS VERY EMBARRASING. HELP