18 year old boy with abdominal discomfort - buscopan didn't help. no vomiting or diarrhea?

Some possibilities..: If a teen has very uncomfortable tummy pain, and is normally in good health, the possibilities include: appendicitis (usually right lower quadrant), constipation (crampy), stomach or intestinal flu; liver, gallstone, or kidney problem; viral, bacterial, parasitic infection; etc... Most people with moderate pain, more than mild pain, may need a doctor's exam to be sure it's not something serious.