New Pain

On my 7th day post-op I venture out to take my handicap son for a drs appt, I was feeling great almost no soreness left. When we started home though I started feeling a tenderness and pulling on the left side of my stomach. We do have a handicap full size van that I had to step up into and i did push my sons wheelchair but didnt feel anything while doing so. the pain was better this morning atfer resting all night, almost no pain this mornin but now this afternoon its back. Is this normal ? Did I prehaps pull something? Its okay except when i move a certain way or bend. Any feedback appreciated.