Could just be a pulled muscle, a torn adhesion (not a bad thing, just a thing), or a kink in your intestine. The fact that it is better probably means it will resolve on its own. As long as the sharp pain is not there and it is improving, you can just wait and see. But, if it persists more than a few days without gradual improvement, call your doctor. Obviously, if it gets worse, particularly if the pain is sever, you need to call sooner. Some of the complications at the stoma site can be obstruction or hernia.