Chris:
A neurologist may help determine if she has Parkinson's. Since she has no money or insurance have you thought about going to a teaching hospital (don't know if you live near a major university. They may be able to point you in the right direction. Or how about contacting a Parkinson's group that might be able to suggest a doctor.
My mom is 74 and was diagnosed with Parkinson's 4 years ago. It started with a tremor in her thumb. Thank goodness she has a great neurologist who prescribed meds for it. Her Parkinson's really hasn't progressed that much - due to the meds. I have no idea why people get it.
Good Luck!