When I was a toddler I'd react bad to milk (not to mother's milk tho)-diarrhea, green poop, rashes on face, etc. so I wasn't given milk, only sour milk products which never gave any reaction. Recently I drank milk protein tho, didn't get any reaction, although I haven't drank full milk but I do remember years ago sipping it when making yoghurt for biology homework, don't think I had any reaction so it might've been when I was younger.