Tommy, who is three years old, attends with his mother who is concerned about his cough. She explained that his current illness began 2 weeks ago with coryzal symptoms and intermittent low-grade temperatures. However, over the last four days he has also developed a cough. She is finding the cough very distressing as it happens in bursts, following which he vomits, and describes episodes are worst at night. Whilst examining Tommy he has an episode similar to what his mum described. He otherwise appears well and his observations are normal.
Given the most likely diagnosis what is the most appropriate next step in management?