I have lower back just below rib cage left side pain. Is this related to my kidneys? Shouldi be scared?

It could be. Pain from your kidney typically occurs in the flank region, which is located in your lower back just below the ribcage. You should see your doctor for further evaluation and management.
Possibly. Left side or flank pain can very well be related to the kindeys as this is the location for kidney pain. However you could also be experiencing musculoskeletal pain as well. Other symptoms such as pain with urination, blood in your urine, or tenderness to the touch could help determine the cause and source of your pain. You should see your healthcare provider for evaluation.