I fell down the stairs yesterday morning and a few hours later, noticed when I went to the restroom, had vaginal bleeding. I do not see any blood in the toilet, but only when I wipe. I am on birth control and not due to start my cycle for another week. Can a hard fall cause you to start your cycle, or would it be something more concerning? My entire back from the middle down is very sore and bruised near the tail bone and buttocks.