pain/discomfort in abdomen during sex

Lauren • I'm only human, born to make mistakes
So my bf and I were having sex today and we got into doggy style (or from behind w//e) and whenever he would pound into me I would feel a pain somewhere in the right side (from doggy position) of my abdomen? It happens sometimes when we do that position but it really hurts and feels uncomfortable. I'm not sure what it could mean, any suggestions?