I had DS fall on my belly while I was lying on my side a couple of months back. it was really painful and the pain lasted pretty much all day. When I called my ob she asked if I'd had movements since then, so once I did feel them again, and the pain eventually went away (must have been bruising i think) I stopped worrying about it. Generally speaking, I think if something's wrong you'll know - there will be bleeding or no movements. So your baby's probably fine, but I agree with Rach75, call your doctor or hospital and check.