i think i have torn my rear delt/ muscle in the shoulder

basically i was watching tv and scracthed my back-kind of the way u have a dumbell behidn your head for tricep excercise
except i didnt have a weight

i brought my elbow down towards my side and felt umthin move wer my delt is

its giving me a very uncofmrotable feeling and if i try lifting something i can feel its torn it give a feeling like its unattached

i have bene to the hospital but the nurse said its fine
told me its fien because i can move it about

what should or can i do about this


and has anyone else had this injury

sorry about the vague description