hahahah it might be as well the reasons behind kidney stones aren't fully understood still, some people may develop them without any history of previous disease's or family members affected by it.

if skipping milk reduce his symptoms (or at least works as a placebo), all the power to him!

The one I had (which is most common) has two parts, calcium and oxalate. So definitely milk could be one side of the coin, but you can't cut out calcium altogether because your bones need it. The list for each side of the coin goes on for a bit (not too much nor too little of this or that in your diet over possibly a decade).

If I have a second kidney stone, then the doctor said they'd have me pee in a bucket over 24 hours to see if they could get a little more exact on the cause. But what if I had been going through a 2 pound bag of spinach from a big box store (oxalate) or had been binging some ice cream (calcium)? Wouldn't that throw off such isolated data?

Anyways, this device could be an interesting "peeing in a bucket" type data collection over time which could help isolate which side of the coin my kidneys are having issues with.

Completely anecdotal but the 1 person I know who’s had kidney stones in his late 20s is a friend who drinks milk regularly, every day. Loves the stuff.