Im A First User Of A Birth Control Pills. I

Im a first user of a birth control pills. I started taking it on march 16, the first day of my menstrual period with no interruptions my period lasted 3days with spotting only. 3 days from now i started taking vitamin E in the morning. Yesterday morning i had this watery discharge with a pale red blood in it. I wonder what was those? Is it related to the vitamins or the pills am taking not fits in me? Thank you.