Having doubts.

Denver area. I'm almost 76.
Around September of 2021, I noticed bumps in the sides of my neck - more on the left side than the right. Around November, my PA wondered if it might be cancer, but out of skepticism & fear, I poo-pooed that. In March of 2022, they did some tests & discovered Lymphoma. Had also had a 5cm bump in my right groin, by then. But thank goodness, it hadn't metasticized.
From June to December, 2022, I underwent "the strongest chemo" they had. So far, so good - 3 MRI/CAT scans negative for cancer.
I'm left with a twitching left thumb, when that arm gets chilly, but have also had thick saliva and slurred speech at times. I have to work at the speech when it gets bad. They also imaged my brain & it's ok. I also have problems with swallowing food & drink into my lungs - epiglottis, and choking up food. I also get brief flashes of unfocused vision since around 2021.
So the PA was saying, maybe Parkinson's. They sent me to a Neurologist who thinks "maybe atypical Parkinson's". They're sending me to a Parkinson's specialist ( partner of the Neurologist ) in 2 months.
But if Parkinson's has no blood test, I have doubts. Since 2020, I have a deep distrust of medical doctors.