You can try lactose-free or lactose-reduced dairy products, which you can find at most supermarkets. Another option is to take lactase enzyme drops or tablets before you eat dairy.
Some studies show many people can eat dairy if they choose low-lactose foods like hard cheeses, eat foods and drinks with lactose in small amounts, or use dairy as an ingredient in a meal. Since dairy is the best source of calcium, it's worth experimenting by adding small amounts to your diet to see what you can handle.