What Causes Vaginal Bleeding During Sexual Intercourse?

Hi, i have been bleading during sex for the last two months I dont have sex often maybe once a fortnight or so - the last three times I have bleed , yesterday there was lots of light red blood. Today I have had a ripping feeling in my lower stomach area. I am going doctors tomorrow but am very worried now.I had abnormal cells in 2005 and had coloposcopy, I also had a smear earlier in the year that was all ok?