Was the onset sudden? Were you lifting something heavy? For the time being give rest to the affected shoulder, avoid overhead activities or any activity which increases the pain...can take any painkiller along with local application of ice fomentation and gel. It should settle, but if no improvement in a week then visit an orthopaedic surgeon to get evaluated.
Next Steps
Rest, ice pack, avoid painful activity, use painkiller
Health Tips
if no improvement in a week visit an orthopaedic surgeon for evaluation.