That’s highly unusual level of intolerance. A whole cup of butter contains only 0.1 g of lactose, and since cup of butter is 1500-2000 calories, in a typical me

That’s highly unusual level of intolerance. A whole cup of butter contains only 0.1 g of lactose, and since cup of butter is 1500-2000 calories, in a typical meal that includes butter you’ll consume much less than that. If you just use 1-3 tsp of butter for frying, and then don’t consume everything you cooked, you’ll be consuming less than 1 milligram of lactose. For comparison, most people with lactose intolerance can consume around 10 grams a day, that is, 10 000x times as much. What you describe looks more like allergy than regular lactose intolerance.