Hello Jean. No one can diagnose your husband’s dizziness except his Neurologist. Each of us with Parkinson’s are different and have symptoms others may not have. It would be wise to call and get in to see his Neurologist or Movement Disorder Specialist to determine the cause of his dizziness. He may need an adjustment on his PD meds, if not the doctor can find the answer. Otherwise, our guesses on this site as to what is causing it can do nothing but cause you more worry. You and he are both wise for realizing he should no longer drive. I don’t like it but I can’t drive anymore either. Be at peace and find your answer from his doctor.
Praying for you
Carol

I have vertigo quite often. I find that Physical Therapy helps.

I hope by this time your doctor has discovered the cause of your husband’s dizziness. I want to remind you that if he has Parkinson’s his reflexes, his reaction time, & possibly like me, his judgement, & the ability to think & make decisions quickly have declined. Acknowledging the fact that you shouldn’t drive can be as difficult as giving up the keys. It is another loss in your life you now live with Parkinson’s, but a wise decision. Both of your lives have value, and you value the lives of others by not driving. Thank you & God Bless you both.
Carol

Yes, I experience dizziness ocasionally. Due mainly to orthostatic hypotension.
When standing from a sitting or lying position, the blood pressure drops. My neurologist is trying a couple of different medications to help offset this.
Some relief but still "experimenting".

It could be Benign Paroxysmal Positional Vertigo (BPPV), which is very easily treated. Otherwise it could be related to his blood pressure or blood sugar. It could be a reaction to medications. He needs to see a doctor.