Stomach gas: What's wrong and how can it be cured?

I am aged 63 and have been a moderate drinker (about 25 units/week) for many years. Last summer I developed pain and discomfort just below the rib-cage and started producing large amounts of stomach gas. Suspecting alcohol to be a factor, I cut out drinking. Blood tests showed normal liver function, while an ultrasound and a gastroscopy showed no abnormalities. Nine months on the symptoms are still there. My GP seems baffled. Any suggestions on what is wrong and how to cure it?

Dr Fred Kavalier answers your health question:

You could be lactose intolerant. Lactose is the natural sugar that is present in milk products. People who are lactose intolerant cannot digest it because they are lacking an enzyme called lactase, which breaks lactose down into glucose and galactose. Undigested lactose ferments in the stomach, causing a build-up of gas. Even if you were not lactose intolerant when you were younger, you may develop it, as it becomes more common with age. If you don't want to take a test to see if you are lactose intolerant, you could try to reduce or eliminate lactose from your diet and see if you are any better.

Please send your questions and suggestions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182 or e-mail to health@independent.co.uk. Dr Kavalier regrets that he is unable to respond personally to questions.