Hi, Welcome to Health care magic forum.
As you mention you had dislocation of the shoulder 6 months back. and there would have been pressure on the brachial plexes , and have recovered ,there would have been recurrence again now.
Or the twitching might be due to the
arthritis of the thumb joints.
I advise you to consult an orthopedic surgeon for diagnosis and treatment .
I usually prescribe to my patient with such symptoms injections of
vitamin B1,6,and 12 for10 consecutive days, and then periodically.
protein supplements, calcium, multivitamins,
diclofenac, and
paracetamol.
Avoid taking potato, other tubers, tomato, egg, chicken, and sea foods.
Wishing for a quick and complete recovery. Thank you.