How do i know i've ped a kidney stone?

A month ago i went to the hospital with the worst pain ever. i thought i was going to have a baby, but i knew i wasnt pregnant. well it was that i have a kidney stone the size of a pebble, whatever that means. The doctors told me that it was in the eureter. i asked when it should come out. they said in about two days. so far i havent seen anything, and besides they said i will experience extreme pain and so far nothing. could it be that it ped already or its just there? any ideas.