How to turn my urine into acid?

Hey,

The chemical analysis of the latest kidney stone that came out few months ago indicates the presence of calcium, oxalate and carbonate. Because of the carbonate is likely it is an alkaline kidney stone.

Right nowI have a kidney stone passing that seems too large to come out. I guess it is also akaline and I would like to make my urine acid to induce an acid-alkaline reaction that, I hope, will dissolve the stone.

There are aliments or suplements that have one PH outside of the body, but after ingested they turn to the oposite. For example, lemons that are acid turns alkaline in the body. Milk that is alkaline turns to acid in the body.

The question is:
How to make my urine acid?
Acid ascorbic or acid malic may be options?

I cannot drink milk because of allergy.

Sukhoi