What are the symptoms of Parkinson's?

From my reading, it appears that both Parkinson's and ET can effect one side of the body. It doesn't sound like that is going to be the deciding factor.

Thanks guys, just one query. Does Parkinson or ET affect only one side - my mom complains of these sensations only on her left side.

One neurologist gives the diagnosis as Essential Tremors, and another thinks it is Parkinsons. This is not terribly surprising, as the two conditions have things in common. Here is how the Mayo Clinic compares the two:
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Essential tremor vs. Parkinson's disease
Many people associate tremors with Parkinson's disease, but the two conditions differ in key ways:

Timing of tremors. Essential tremor of the hands usually occurs when you use your hands. Tremors from Parkinson's disease are most prominent when your hands are at your sides or resting in your lap.
Associated conditions. Essential tremor doesn't cause other health problems, but Parkinson's disease is associated with a stooped posture, slow movement and a shuffling gait. However, people with essential tremor may sometimes develop other neurological signs and symptoms, such as an unsteady gait (ataxia).
Parts of body affected. Essential tremor mainly involves your hands, head and voice. Parkinson's disease tremors usually start in your hands, and may affect your legs, chin and other parts of your body.
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(To see the full article, do a web search for Essential Tremor Mayo Clinic.)

Is there a Parkinsons specialty clinic in your area? You might seek a third opinion from professionals who are experts at diagnosing Parkinsons.

Has your mom had treatment for the BPPV? A friend of mine has/had that and I know it takes a while to resolve.

Here's the National Foundation for Parkinsons with info about how it is diagnosed.

http://www.parkinson.org/parkinson-s-disease.aspx

There is also Parkinsonism which can be caused by medications or other illnesses. Be sure to check that out on that website.