As I recall (not a way to get reliably accurate information), an excess of Levodopa can cause heart flutters, eyelid flutters, and all sorts of odd symptoms. Is this a case of "this is an old guy who doesn't matter"??? I'm sure these people can be convinced that human suffering is human suffering, and that they could consult with a clinical pharmacologist to ascertain the effects of various drugs. As a backup, rxlist.com is a place to start. A starter dose of Sinemet might help, I would guess, as a typical first choice for older people, but see parkinson.org or one of the other charities' websites to find out about the medications and where to find a doctor who knows PD. Just a neurologist is too much of a generalist in many instances; most of us rely on at least a consultation with a Movement Disorder Specialist (MDS), a subspecialty of Neurology.

You are a wonderful person to look out for your dad like this.

Best of luck,
Jaye