hello laddhn,
                   shoulder pain- may be due to- bursitis or tedenitis, 
frozen shoulder, 
rotator cuff tear, calcific tendenitis, shoulder instabilty, shoulder dislocation, arthritis, SLAP lesion, 
labral tear, shoulder separation, it is serious if associated with-inability to carry object  ,deformity,pain at night or while resting, inability to move arm,swelling &bruise, fever, redness ,warmth in this condition immediately need orthopedic surgeon help,-investigation- X-RAY , 
arthroscopy, MRI of shoulder joint, treatment- rest by sling,ice in acute injury within 48 hours, heat more useful in chronic cases,phycial therapy,TABLET-NSAID(brufen 400mg trice daily after meal for 5 days) , in medical condition- diabetes mellitus- frozen shoulder common, in 
gall bladder disease, liver, heart &cervical disease - compilants pain in shoulder , hope my advice is useful to you, thank you.