Thoracic outlet<unk> 
Vertebrobasilar insufficiency
Syncope
Vertigo
Traumatic/Acute:
Shoulder Dislocation
Anterior shoulder dislocation
Posterior shoulder dislocation
Inferior shoulder dislocation
Clavicle fracture
Humerus fracture
Scapula fracture
Acromioclavicular joint injury
Glenohumeral instability
Rotator cuff tear
Biceps tendon rupture
Triceps tendon rupture
Septic joint
Anterior shoulder dislocation
Posterior shoulder dislocation
Inferior shoulder dislocation
Nontraumatic/Chronic:
Rotator cuff tear
Impingement<unk> 
Calcific tendinitis
Adhesive capsulitis
Biceps tendinitis
Subacromial bursitis
Cervical radiculopathy
Refered pain & non-orthopedic causes:
Referred pain from
Neck
Diaphragm (e.g. gallbladder disease)
Brachial plexus injury
Rucksack paralysis
Axillary artery thrombosis
Thoracic outlet<unk> <unk> 
Pancoast tumor
Myocardial infarction
Pneumonia
Pulmonary embolism
Neck
Diaphragm (e.g. gallbladder disease)
Rucksack paralysis
Subclavian steal syndrome
Thoracic outlet syndrome
Axillary artery thrombosis
Vertebrobasilar insufficiency
Superior vena cava syndrome
Syncope
Aortocaval fistula
Vertigo