My wifes stomach burns when she has milk, yoghurt, ices cream and cheese. But I read up that burning stomach is not a lactose intolerance symptom?

Heart burn. isn't caused by lactose, rather by fats in dairy, or any other fats, caffeinated beverages, etc .. Lactose intolerance causes flatulence, diarrhoea, indigestion, and other lower gastrointestinal symptoms. Avoid dairy fats or use in moderation, use an antacid, see doctor if no improvement, wish you well.