What Does A Bubble On Lower Back Indicate?

Hi, I have what seems like a bubble on my left lower back. Right on spine but off a bit to left. I have pain that goes from there to what seems to be my groin. Wondering if that is the source or could it be something else? Have had it for years. Relatives and friends have all felt it. Wasn t too sure what it was or if there is a cure or if I should see a doctor about it?