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.
In 2003, scientists at Newcastle University found that sage had a beneficial effect on memory. They used capsules that contained 50 microlitres of sage extract in sunflower oil. Have a look at the label on your capsules to get a dose similar to this. A few patients may develop raised blood pressure when taking sage, so if you have high blood pressure, avoid sage.