Yeah my dad has been looking at me shaking his head from side to side for the better part of 50 years now.
you didn't say if he has hepatitis or not. this is a hepatitis forum. he should be seen for this condition, there are no doctors here and what you describe could have many causes, he many need to see a neurologist to obtain a diagnosis, certainly he will need tests to determine what may be causing his symptoms. he could start by seeing a primary care physician to obtain the referral to a specialist. hope all works out for you.