Hi there -
There is no way to know until your tests come back. We can speculate until next week, and not know for sure, and by then, your results will be back lol.
I don't know a lot about kidney stones, but my ex bf used to get them, and his doc told him that once a male gets kidney stones, he is more likely to get them again. You'll know in a couple of days if you pass them.
And throw out the nylon underwear lol. You don't like them, they aren't good for your skin, etc. That way you won't be tempted to wear them on low-laundry days. :)