As I have gotten older.. The more liquid a dairy product is, the less I can tolerate it...
I can use milk, sour cream, buttermilk, cheese and like to cook with and all is OK.. I can eat a small gob of sour cream or cottage cheese on a baked potato OK... No more than 2 times a year will I eat a bowl of cereal with milk... And when I do, I have consequences...
My 5 cents of experience...
Here's what I've found about milk and my body.
I drink about 3-4 glasses of 2% milk every day. A tad over 2 gallons a week. I also eat a cup of yogurt almost every day. I eat cheese, ice cream, sour cream, all things dairy.
With that said, when we go on vacation, I don't get that quantity of milk. After a week or two, if I start consuming milk again, I get a gurgly gut for a day or two. And my normal amount of glassiness returns as well. Then I'm back to normal for me.
I suppose anyone that consumes a consistent diet gets used to consistent results, and anything that then veers from that consistency will give them different results.
I'd guess (an opinion, not fact) that lactose intolerance for some, is that their body turns dairy into horrible gas and discomfort but it's not a medical problem.
However, for others, it may be a real medical problem if they have allergies or diseases/conditions that dairy products would effect negatively.
If you find a food that disagrees with you consistently, your body is telling you that either something is wrong with your body, or, you may have an allergy or physical ailment, or, your body just doesn't agree with that food at the present and you don't want to take time to adjust to that in your system.
It would be best to find out why your body disagrees with that food, just in case there's an actual medical problem.