How are you? Renal colic is a very severe pain that can present suddenly and without warning. It is usually caused by stones in the kidney, renal pelvis or ureter. The pain is caused by dilatation, stretching and spasm of the ureter. It can present with pain, hematuria, dysuria, frequency, urgency etc. Treatment involves conservative or surgical mangement.
Treatment depends on the size of the stone and duration of presence of stone in the urinary tract and complications present. Most symptomatic renal stones are small (less than 5 mm in diameter) and pass spontaneously. Stones larger than 1 cm in diameter usually require surgical intervention. I think in your case they have waited for the stone to pass spontaneously with medical management.
Signs like reduced renal function, fever, complete obstruction of urinary tract can indicate immediate surgical intervention. But in your case none of the above mentioned complications were there so they waited for the stone to pass spontaneously. You can get a ultrasound and kidney function test done to assess the status of the kidney.
I don't think a 56 hour wait could have caused damage to your kidney, because if it had caused you would have had fever, anuria, severe intractable pain, vomitings etc. The stent would help the stones to pass through the ureter as well as maintain the passage in the ureter.
All the best.