Dealing with symptoms can be overwhelming. Parkinson’s symptoms are a part o vicious circle of this disease. This is why most people give up working on their recovery.
Best thing to do is to be patient and talk to your “friend” while symptoms rage. Share everything with him. Smile with him. Especially in this situation.
Parkinson’s is teaching us a lesson. We are not in charge of the universe, God is. There is letting go required.