I have recently been experiencing bleeding during sex. I've been sexually active for about 4 years and this has never happened before. I thought it could be caused by the size of my partner, but we've been seeing each other for about 8 months & the bleeding has only occurred during this past month. The only thing that has changed is now I'm on the pill. Any advice is greatly appreciated.

How much bleeding? A few drops, enough to fill a pad, buckets full?

There could be many reasons for this, none of which we can accurately diagnose online.

Your best bet is to see your doctor.