What Causes Vaginal Bleeding And Brown Discharge After Taking Yasmin?

I am freaking out because I have been bleeding each day for the last few days, it started with a brownish discharge. I am on the pill yasmin and I was on antibiotics for my sinuses when my break was due but I carried onto the next pack because my pharmacist told me to. I have never bled inbetween periods whilst taking the pill I did forget it one day but doubt would cause this as took it as soon as remembered. The reason I am panicking is because I had an abnormal smear test (the nurse said the lowest abnormal 1) and have to wait 6 months for next smear and when you research online says bleeding sign of cancer...