Hello My Kidney Is Aching. I Hade A Test At

Hello my kidney is aching. I hade a test at Dr & they said I didn't have an infection. What do you think is going on? Dr said It might be a muscle spasms. The aching doesn't feel like muscle spasms. I have muscle spasms in my upper back & shoulder several times a month & the kidney aches is different. It feels like labor pains.
Thank you
Robin