What Dale is talking about is Benign Positional Vertigo. It isn't caused by PD (I had it a few years ago) but can cause extreme dizziness.

In PD, some of the meds can cause Orthostatic Hypotension, aka low blood pressure when standing, which makes you dizzy. Talk to your doctor.

Yes indeed. Parkinson’s affects many things. Dizziness in Parkinson’s is generally due to a misalignment of crystal in the ear. There are PT’s who can realign these. Get a referral.