Pain From Traveling?

I am almost two years post op and rarely travel When I do, it's usually no more than four hours in the car. Thursday we took my oldest to college and spent roughly fifteen hours in the car in one day. Since then I have had pain in my left side, just left of my port. I noticed it started in the last four hours or so of the trip and feels like a pulled muscle or like a "stitch" in my side. I could feel my port "rubbing" on my ribs the last part of the trip as well, probably from not sitting with good posture. I am concerned because we have to travel ten hours two days in a row, and if it still hurts like this, I'm not sure what I'll do. Has anyone experienced anything like this? I am going to try heat today and see if that helps. Any help would be greatly appreciated