I have a swollen shoulder going to my back and it also affects my neck and hand ...i would like to know what causes it.

Swollen shoulder: Trauma? Overuse? May be bursitis ( swelling of sacs that surround joints), or rotator cuff tear or even cervical disc disease. Would consider shoulder xray ( for arthritis) and then MRI to view rotator cuff and bursa) as well as cervical spine MRI . The hand pain may be from nerve impingement so would follow up this week as a shoulder steroid injection may alleviate the symptoms f/u/ w/ doc

Usually SWELLING,: enlargement/puffiness due to fluid accumulation, is quite difficult to see in the shoulder. But when present is most likely due to trauma, similar to other sites of swelling. This may not have been recognized when it occurred. Infection also a cause but usually heat/redness/tenderness also present. Lymph obstruction due to growth/tumor or an inflammatory condition? Expert eval by Doc/Ortho needed