A 47-year-old woman presents with intermittent loose stools and abdominal pain relieved by defaecation for 6 months. She reports bloating but denies weight loss, rectal bleeding or nocturnal symptoms. Family history is negative for colorectal cancer or inflammatory bowel disease. Physical examination and basic blood tests (including full blood count and C-reactive protein) are normal. According to Australian recommendations, which is the most appropriate next step?