As your kidney stone is not seen in the recent Ultrasound
abdomen,pain due to stone can be ruled out.
Most probable cause is Injury to the Urinary tract
during the procedure.
If the pain is not relieved by Anti inflammatory drug and smooth muscle relaxant
,other causes for pain in the lower right side of abdomen has to be ruled out.
Most common cause is Chronic Appendictis.Unless it is grossly enlarged ,it cannot be seen in ultrasound.
You have to go for CT scan abdomen with Contrast to rule out other causes of pain abdomen.
I will be ready to answer your query once you come back with CT scan abdomen.
Wish you good health