Your history is suggestive of a poor lifestyle lacking any physical exercise. You may be engaging into a lot of activity at home considering it as exercise but there is a difference between physical activity and physical exercise.
Also as you have a history of
diabetes it could possibly be a case of beginning of periarthritis shoulder
Leg pain is not related to shoulder pain However it could be because of lack of flexibility in the lower body which may be making it difficult to sustain prolonged postures such as prolonged standing/sitting.
Also as we age there is a loss of muscle mass called as scopenia which may be adding to your symptoms.
Next Steps
you may connect with me . I conduct virtual exercise sessions thrice weekly for people with comorbidities such as
diabetes. you need to first treat your shoulder and then worry about your legs etc.
Shoulder should be your priority as with poor mobility , and pain your shoulder may become progressively weak and prone to other issues.
Health Tips
avoid lifting heavy bags from affected shoulder
avoid sleeping on affected side
use pillow when side lying
don't avoid movement just because it's painful. sometimes movement is what's required to improve the nutrition to the joint.