What Causes Headache And Dizziness While On Micro- Oval Pills?

I WAS USING A TRIGESIL PILLS FOR 5 YEARS, LAST MONTHS I WENT TO CLINIC FOR FAMILY PLANNING AND THEY TOLD ME THAT TRIGESIL PILLS ARE NOT AVAILABLE SO THEY GAVE ME Micro- Oval I STARTED USING IT , I STARTED TO HAVE HEADACHE, FEEL DIZY SOMETIMES MY DISCHARGE COME WITH A LITTLE BLOOD I COUNTINUED WITH THEM UNTIL MY MINSTRUATIONS SO I STARTED MY PERIOD ON 9 JUNE . ON THE 21 FIRST A WENT TO CLINIC AND TOLD A NURSE THAT MY PERIOD DOESNT STOP BECAUSE I USED MICRO OVAL PILLS SO THE GAVE ME BRUFEN N 3 PACK OF TRIGESIL I STARTED TO USE THEM THE MENSTUATION STOP AFTER I COMPLEATE THE WHITE PILLS, AFTER 4 DAYS I STARTED TO SEE AGAIN SOME BLOOD BUT NOT HAVE , REMEMBER NOW IM DRINKING THE YELLOW ONE TABLET NEXT WEEK ILL BE DRINKING THE RED ONE SO SHOULD I COUNINUE TO DRINK UNTIL THE RED ONE , PLS HELP