I highly recommend:
The Frozen Shoulder Workbook: Trigger Point Therapy for Overcoming Pain and Regaining Range of Motion Paperback – August, 2006
by Clair Davies NCTMB (Author), David G. Simons MD (Foreword)

Irony is an ortho doc commented my shoulder would never improve until I had rotator cuff surgery. It was painful and stiff, couldn't through a ball overhand only underhand. So with the book and a theracane, after a year I was able to spin my arm around in a full circle! Amazing! Never had rotator cuff surgery, either!

Fast forward 10 years... Dx of PD. I suspect the frozen shoulder was just one of the issues that was PD/Dystonia related but never realized it.

Yes, I still have my book and still refer to it. Between local PT classes for PWP, and David Zid's book I'm doing great.

Thankfully my MDS does accept that PWP do have pain in their bodies. LSVT BIG got me moving, and daily stretching makes a huge difference. The pain is still there, but it is a great day and time to keep moving.