If you are in the US, you can use this to help find a clinical trial near you (in the UK look on the Parkinsons UK website).
https://foxtrialfinder.michaeljfox.org/

I can appreciate the severe pain that you are experiencing. My wife is in the same boat as you. We are trying physical therapy at home primarily. If you are able there is a series of moderate exercises: The Complete Healthy Back System: Back to Life. It is basic core exercises, but you can do series one while seated. You can find these on Youtube.com. She has found TENS to help for a 2-3 hour period. You need a good TENS unit with at least five different programs and four electrodes. Maybe you have found this to be of no value. Are you able to use a walker? If so use it. You are in my prayers.

Yes and pain pumps and...... a lot of other things. Only thing that works enough for me to function is morphine and muscle relaxers. I have tried all kinds of treatments and medications. Still hoping for something to help with the back issues and the PD.

I have had the shots and they do not help me at all. I tried all kinds of meds and the only thing that helps me to function is the morphine and muscle relaxers. Without them I am not able to do nothing but stay in bed.

I take Extra Strength Tylenol - can take 4 a day, It helps, Going to Dr next week about getting a shot in my back,