Unprotected Sex, Light Vaginal Bleeding. Taken Many Ipill's. Causes For Bleeding?

Hi ! I had taken ipill number of times in a month and now i find vaginal bleeding . It is very less and light but the bleeding increases for some time after sex. I had sex without protection just 2 weeks ago and had taken ipill. I am worried about the bleeding that is continuing . At times it is very less. and is happening since last week. I had taken about 5 to 6 ipills since June to till date. Please let me know what might be the reason and when will it stop.