Pain in left side, back, and ribs. normal ct scan. the pain is worsening every day and first began about 1 1/2 years ago. what's going on?

Multiple causes: Causes of left-sided back and rib pain may be due to musculoskeletal conditions such as costochondritis, intercostal neuritis, Quadratus Lumborum muscle strain, degenerative joint disease, and degenerative disc disease, which may readily seen on computed tomography scans of the chest and abdomen. Other causes of left-sided rib and back pain may be due to referral pain from internal disorders.