I get stomachache when standing for a long time. what is the reason for this?

Unusual symptom: Do you experience upper,middle, or lower abdominal discomfort after prolonged standing but otherwise not get similar discomfort on other occasions? This might be abdominal muscles which become uncomfortable in a strain type way as you stand upright for prolonged periods similar to people who develop back pain on prolonged standing. I doubt that any intestines or other intraabdominal organs do this