DS used to kick me in the ribs constantly. It hurt. I actually bruised on the outside. I don't remember when it started. I know that I am 28w5d and I have felt LO's movements close enough to the ribs that it could happen. Sometimes its the feet, sometimes its the hands, I even think it can be the head or butt sometimes. I don't think position matters. What matters is where they are pushing to try to stretch out or get some room. It could very well be the baby causing that pain. That said, it seems a bit early to really be hurting yet. I know with DS I could feel it for a while before it became painful. The pain I think started near the end- the last month or so maybe?