Shoulder pain is very common and affects one in ten elderly adults.
The shoulder joint is held in place by the rotator cuff muscles which attach the arm to the torso. These muscles are responsible for pushing, pulling, rotation and lifting the arm overhead. Due to the wide range of movements in the shoulder joint, it is also prone to a range of injuries such as rotator cuff tendinitis (informally also tendonitis), shoulder impingement, shoulder bursitis and frozen shoulder.
These injuries and diseases can cause mild to intense pain resulting in some cases in the complete loss of movement in the joint. Many shoulder problems can fully recover on their own after a couple of months of rehabilitation. Always consult a doctor when the pain is too severe to carry out daily activities, when you have shooting pains, numbness or shrinking of the shoulder muscles.
Keeping the shoulder mobile is the best way to beat the pain. Don't avoid doing certain tasks, instead modify them to become pain-free by moving differently, not staying in one position for too long and by taking breaks from repetitive work to stretch.
Do the following movements:

Back bend: Hold a foam roller or a thera-band with both hands in front of the body. The hands should be wide apart. Lift the foam roller or thera-band overhead and reach as far back as possible. Keep a straight back and the head alignment neutral and over the spine. Hold for 60 seconds and recover to starting position. Repeat 10-15 times.

Recovery position: Start on the hands and knees. Lower the buttocks down to the heels and press the head between the arms. Flatten out the back. Hold this movement for 60 seconds. Repeat 3 times.

Arm roll: Lift the arms up to the sides to about shoulder height. Start with the palms facing forward. Roll the arms forward so that the palms twist from facing forwards, to downwards, backwards and finally upwards. Roll back to the starting position. Roll the arms backwards in the same manner until the palms are facing to the back. Repeat 10-15 times alternating between forward and backward rolls.