Thank you for your query.
1. The possible cause are:
a. Post strep neuropathy. Get a Neurologist's opinion.
b. Cervical spondylosis
. Get Cervical Spine X-rays done.
c. Fatigue and muscle weakness
d. Calcium, Vitamin D and Vitamin B12 deficiency
. Get his blood tests done.
e. Carpal Tunnel syndrome
. Does he spend a lot of time on his mobile phone or computer?
2. You may share the test results here for further treatment options.