Probably best to follow your doctors instructions and follow through with an IVP, although urologists tend to stay away from them these days due to the nature of the contrast they use. I would find out what TYPE of contrast they're going to use, and if it's Gadolynium... tell him NO, and request a no-contrast-abdominal-CT-with-stone-protocol.
As for you being diagnosed with stones but not feeling any pain... count yourself lucky my friend. They're either a) too small to pose any significant pain issues and will pass with no problems, or b) they're in one of the poles of your kidney that don't pose a threat to falling/travelling down the ureter and into the bladder (which is extremely painful).
You know, on second thoughts, ask for the CT an s kip the IVP all-together. The CT will be a heck of a lot more accurate, and although it's exposing you to more radiation than the IVP, since it's a one-time diagnostic occurrence, you shouldn't have much to worry about.
Good luck!
LMNO