How could you treat small shoulder tendinitis?

Different: There are different approaches. It will actually depend on what shoulder structure(s) is/are involved. If it is rotator cuff (by far, most frequently involved), exercises, physical therapy and also a steroid injection may be helpful to relieve the pain and restore the function. Also, avoidance of movements/motions known to cause/aggravate the pain is advisable.

Small=mild?: If u mean minor the rx is usually directed at the rotator cuff: pt, otc nsaids & activity modification . Best 2 start with ortho eval and imaging , & follow his protocol 4rx.