What all must I stop eating if lactose intolerant?

Spreadable and drink. Milk products that are drinkable and spreadable have high blactose contenet. Lactaidev milk and ice cream predigest lactose and may be used.
Lactose foods... Milk products/ dairy. There are different levels of allergy. Some patients can eat yogurt and cheese, others have to avoid all dairy. And dairy containing foods... Look for label with lacoste, milk in label. Soy products are good options. And new lactose free dairy products are becoming quite popular! Best to you!
Read labels. Lactose intolerance is not an allergy and no reason to NEVER consume anything with lactose in it. Just avoid the type of foods that are high in lactose. Milk, soups with milk, spreadable cheese, creamy additives are high. Sharp cheddar cheese is low. Some lactose milks have added the enzyme so you can drink them without problem. Your system will guide your selections if you let it.