Suffering from a terrible pain in lower back that lasts a second or two, please advise?

I have been suffering from a pinpoint pain in my lower back, at exactly the same location at least 3 to 4 times per day. the pain stays for a second or two and then goes away. But it happens often, several times a day. I had a lumpectomy and lymph node operation 2 months ago. Can it be related to my operation. My doc thinks no.

Age: 38
Female
Medications: