I have had a feeling of periodic tightness in my lower/central left back. It gets worse with sitting for long periods of time, and if I sit for long enough, the tightness changes to pain . I went to a massage therapist who said I have a knot where the tightness is. When I feel that area of my back, it seems like maybe it is slightly swollen? But I am not sure - I also have (relatively mild) lumbar scoliosis , so I can t decide if that s just the way my back is structured. The area hurts when I press on it. I went to the doctor who said it was right where my kidneys are so she sent me to have an ultrasound , but they found nothing. Normal kidneys. It hasn t gone away though. Any advice?