Fri. Got ureteroscopy & no stone was found dr said I mustve passed it. I still have lower back and flank pain and I have a stent did I really pass it?

Possibly. While it is possible that you passed the stone before the procedure, it is also possible that the stone was pushed back into the kidney during the ureteroscopy. Suspicion of this maybe the reason that the stent was placed. In all likelihood your current symptoms are from the mere presence of the stent.
Ureteral Spasm. Ureter could still be irritated and inflammed with resulting spasm. You might ask your urologist about using a smooth muscle relaxant like bentyl(dicyclomine) or other newer anticholinergics which may relieve some of these symptoms.