Hello buddy, get a kidney function and plain CT scan done. Ureteric stones upto 6 mm can pass out with medication if you are not having any symptoms, have both the kidneys, and normal overall renal function. You need to know the exact size of stone on CT scan. Often stones appear larger on Ultrasound as compared to CT. Good luck. You can go through this short video to understand the damage done by larger stones. https://youtu.be/CPs1rwIyQ4I