This happened to me a couple month ago. Had to stop deadlifting and doing any standing rows for weeks. It is just now better. her is a thread I made over on another site after it happened. Doc said I tore the muscle away from my bottom rib.
Last week I was doing my lighter deadlift routine and may have had my belt alittle too tight but I dont know if that had anything to do with it. I was on my last set nothing major heavy but did 405x12 and felt something kinda pull in my stomach on my side up near my ribcage. After the set I realized that it was hurting pretty good and stayed sore for a few days. It felt like it was almost gone so this week I felt strong and planned on going heavy. Well after only 2 reps with 405 it hurt so bad I stopped. Well, this sob is soo damn sore that it feels like I may have seperated a muscle from my ribcage. I sneezed this morning and almost brought me to my knees.
Has anyone ever done this and WTF could it be. I guess I will have to lay off DL for a few weeks or so. I swear I am the most injury prone bastard I know. Bad shoulders, bad elbows and now this stomach **** I cant gain for losing!