I Went To The ER With Horrible Pain In My

I went to the ER with horrible pain in my lower right back/abdomen 2 days ago, and after a scan was told I had passed a kidney stone. I woke up yesterday morning with a lot of pain, and called the hospital to verify that it was just one stone in the scan because it felt like I was about to pass another. I was told by a nurse that this amount of pain isn't normal since I'd passed the only stone, and to see a doctor within 24 hours, and to go to the ER if the pain gets severe again. I took some meds and got through the pain in the morning, and felt minor aches in the afternoon on and off throughout the day. The pain continued in waves all evening, but worse. I was just woken up with seriously bad pain again that lasted about 10 minutes, but has gone down again. What could be the cause of this pain in waves? It doesn't feel like passing a stone since it isn't constant, but the amount of pain feels like it sometimes