You need proper examination, diagnosis and treatment. Its seems to be a impingement syndrome of shoulder. Consult a physiotherapist.
Next Steps
Go to a physiotherapist.. Ultrasonic therapy +IFT +Heating therapy +some strengthening exercises will be helpful for sure.
Health Tips
At home.. Rest +hot water fomentation +pain killer gel +no side lying on same shoulder +no cold exposure +no manual exertions +no weight lifting.