Osteoarthritis) could this be the reason i hear and feel movement(grinding) in my spine and pain in legs? have ddd and ss.

Spine DDD: Absolutely, this is a common cause of back pain that can be referred to your buttock and legs. If associated weakness and tingling and numbness that is advancing it is not just arthritis. Hope you are doing exercises everyday for your back because it is the best thing for arthritis of the spine, especially in someone that has had spinal fusions.

Degenerate disc: The sensation or sounds of grinding can be due to arthritis, but does not have to be. Spinal stenosis does not make noise. Spinal instability or spondylolisthesis can be felt as instability, and worsen stenosis. Leg pain can certainly be associated. Please see a good orthopedic spine surgeon to have all of this tied together. Best of luck!