Had a cart fall on my shoulder a few years ago the pain eventually stopped but now its back and my shoulder pops when moved what can I do to stop pain?

See an orthopedica. You may have sustained a traumatic rotator cuff injury or other ligament injury that is causing your shoulder to be unstable. You could potentially have a loose bone fragment in the joint space. Bottom line: have an orthopedic surgeon evaluate your shoulder. An MRI arthrogram may be required. Because you are young, don't delay diagnosis because your shoulder could get accelerated arthritis.