Mom goes stiff when I try to sit her up, is this Parkinson's?

Not being a medical person, I think it could be something muscular or orthopedic as well.

What kind of doctor diagnosed the Parkinson's? A neurologist? How long has she been getting stiff? Does it seem as if it's a muscular response that isn't controllable or as if your mother's reacting to pain?

When my father first saw a neurologist about tremors, he was advised he didn't really have Parkinson's although some of the symptoms were similar. Carb/Levodopa helped control the tremors. After several years and more tests, his neurologist thought Dad may have essential tremors, but didn't have Parkinson's.

Can you get your mother to a neurologist, or even an orthopedic surgeon since the stiffness is in her back, and could be indicative of a spinal issue?

I'm always amazed at the seeming ease you Americans have in getting to specialists. No, mom has not seen a neurologist other than one specializing in strokes, and HIS focus was on a study he was doing on decreasing plaque buildup in the carotid arteries. The only way mom is going to see a neurologist is with a referral from her primary physician, and then it would probably be a 6 month wait and an hour drive to the city. Since mom is deemed palliative that isn't going to happen.
I know muscle rigidity goes with parkinson's so I'm wondering if anyone else out there has encountered what seems to be stiffening up/rigidity of the core muscles?

Are you in Canada? I apologize if I've forgotten that. That would really be inconvenient, and could be dangerous if you have to wait 6 months. That's a real bummer!

Found a list of Parkinsons' forums; someone there might have a quicker and more reliable answer to your question:

google/?gws_rd=ssl#q=Parkinson%27s%2C+forum