Is the pain in her shoulder? She is not able to move the arm overhead, not able to lift and stiff . Pain is worse at night, It can be due to frozen shoulder (periarthritis).
Is the pain at neck region,travelling down the arm and hand and sometimes associated with tingling, heaviness, burning sensation & numbness. It can be due to cervical spondylosis /discitis.
Next Steps
Go to a physiotherapist.. Ultrasonic therapy +IFT +Heating therapy +some strengthening as well as stretching exercises will be helpful for sure.
Health Tips
At home.. Rest +hot water fomentation +apply some painkiller gel +no side lying on same shoulder +no cold exposure +no manual exertions +no weight lifting +no jerks +no long sitting /travelling /driving. Correct posture (sit tall)