TF develops a backache but does not seek help. She is a nann…

TF develops a backache but does not seek help. She is a nanny, without insurance and is afraid she will lose her job if she takes time off. After several days, her back pain becomes unbearable, and she seeks help at the ER. An ultrasound is done, and she is told that she has hydronephrosis of her right kidney due to a kidney stone in the right ureter. How would you explain the hydronephrosis in her case?