It is called as peri arthritis
shoulder and for that you can do hot water fermentation and ice therapy at home. If you have shoulder pain
then the stiffness will develop more that might make the arm to have less improvement which might make you to feel more pain
the arm. And also cervical pillow can be used which might make you to have better posture
of the shoulder neck and arm
It must be due to pressure on one side of the body and due to your bad posture in lying. Pour hot water while taking bath which will help you to get relieved from pain.