Why do i have back problems when i walk or stand to long on my upper right side

Because the pain is : Brought on with activity it is unlikely to anything serious like a tumor, fracture, infection or a referred pain from another organ system like a kidney stone . It is musculoskeletal & may be some degenerative changes that may be best addressed with some core exercises like yoga or pilates. Make sure you are exercising regularly, not smoking & not overweight. If symptoms persist, see your pcp.