It’s probably Neuro Orthostatic hypotension. It’s a separate disorder from PD but frequently shows up, and a lot of meds, especially Sinemet, will exacerbate it. There are Meds which help, but staying hydrated, lots of salt, and tight socks will help. Your doctor needs to know so he can check and make sure there’s nothing else wrong. Also, it helps to elevate your head at night, and get up slowly from laying or sitting, and give yourself time for your body to adjust.
Teresa

I have been suffering from orthostatic hypotention for ~2 years. It was controlled ,at first, by midodrine, but is getting bad again.(BP as low as 55/32 and several falls and pass outs). I started on fludrocortisone but I only tried it for 2 weeks. The supply is not available(Supply chain problems). So I am back to the unsuccessful mechanical measures(Salt, abdominal binder, raised bed head, tention stockingsthat I used at the start.
The fight continues.

Have you spoken to your doctor about the possibility of Meniere's Disease?

I have in the past because a new Dr. I got when I went to the VA insistedI I had high BP I had never had high BP but He insisted I take it. I was out trying to help my wife and I had to sit down on the tail gate of my pick-up could hardly move, my legs felt like rubber. I finally made it in the house and my wife said I; going to take your BP" she is an EMT" It was like 90/50 No more BP medicine.

Teresa: I also take 10mg of Midodrine.