It is due to stiffness, unable to move shoulder up n back. If u have diabetes please control d level of sugar. 80 pecent Diabetes patient suffering from frozen shoulder. Do physiotherapy treatment that includes short wave diathermy n IFT for pain relief and shoulder mobilisation , manual therapy .do regular exercise 3 to 4 times a day like pendulum exs, finger ladder exs on wall to move shoulder upwards n sideways. For backward movement do rod exs, hot water fomentation 2 times a day, don't lift heavy weight. Don't lie on this shoulder . Exs improve d conditions. Tk care.