Not sure what happened

My 16 month old woke up last night so i went and got her to rock her. As soon as i sat down I had this excruciating pain in my upper stomach on the left side that lasted a few minutes. The pain subsided enough to go lay her back down. I tossed and turned all night with the pain and it is still painful even while lying down or moving. What could this be? The baby is still moving like normal but I have pain in the same area whenever he moves.