What Causes Bleeding With Pain After Sex?

Hi, I am a 16 year old girl. Recently I had sex with my boy friend whom I love a lot. I had my first sex on 11 May 2011. I had slight bleeding that time which is normal I think. We had that sex unprotected. But I was sure that I am not pregnant because I had my regular period 6 days after that on 18 May 2011. But we again had sex on 25 May 2011 and that time he used condom. But the problem is, today on 28 May 2011, I am having bleeding and when I wash the blood with hand I face pain. Is it normal? I am very tensed. Need your help.