Hi and welcome to the forum,
I hope you find support to enable you to continue to be such a wonderful friend. I understand it is tough for those people who remain loyal by our sides , as Parkinson's is progressive.
My personal view, Parkinson's is a complex illness difficult to get to grips with, we all have a different set of symptoms, that can vary by the hour, medication tends to be tailored to individual needs.
I am really appreciative of friends who ask me what I would like them to do for me and when. This may be the best way for you to help/support your friend, as she will be the only one who truly knows how she feels and what she really needs.
Maybe encourage your friend to join this forum?
Your friend has dystonia, painful cramps , whilst I have cramping in my hands, feet and sometimes in my lower back I feel for your friend having a full body cramp for 3 hours, as you witnessed it is really painful and distressing for both of you.
There is an incredible woman on this forum who has struggled with dystonia and fought against it, having dbs ( deep brain stimulation).
Her username on the forum is bettyblue, she is inspirational. You can search on the forum to read her posts, she is a very supportive member of this forum.
Take Care and Best Wishes x