How long does it take for kidney stones to pass and when should i go to dr if it doesn't?

It is variable: The size of the stone is very important. The larger it is ,the less likely it will pass. If you have severe pain or especially fever, you need to seek immediate medical attention.

See your doctor.: Kidney stones hurt and you should have pain medication to get you through them. Doctors usually get imaging on the stones to find out their size. If they are more than 7mm they're not likely to pass, less than that they likely do in less than 2-3 days. If they don't there is also medical treatment that ranges from lithotripsy to surgical removal.