This is a reoccurring problem, but it only happens once in a blue moon, usually after I sleep in a bad position or something. There will be a dull pain behind my belly button but if i flex my torso to any extreme the becomes very sharp, as if im tugging something behind my belly button. pressing on it to hard produces the same sharp pain, sometimes even worse. This will usually go away after an hour or two and won't bother me again for a long time, but I'm getting sick of wondering why this keeps happening. Can anyone explain?