Hi I m 28 years old, I started light bleeding on Wednesday 8/24/11 then it continued till today Monday 8/26/11 , my period is suppose to come Wednesday 8/31/11,. I started using an antibiotic on Tuesday 8/24/11 cirpofloxacin, could that be the cause of the bleeding. I seen a few blood clots during those days , size of a pencil eraser.