There are a couple of good articles on this site about Parkinsonism. Parkinson's Disease is a form of Parkinsonism, as is MSA, PSP, Lewy's Bodies Dementia, Vascular Parkinson's, etc. They are all different diseases, not something where you progress from one to another. It is possible that you were told that you had Parkinsonism because it wasn't clear exactly what was wrong, just that you had Parkinson's type symptoms.
https://www.myparkinsonsteam.com/resources/park...
https://www.myparkinsonsteam.com/resources/park...

Parkinsonism vs. Parkinson’s: What’s the Difference? | MyParkinsonsTeam

https://www.myparkinsonsteam.com/resources/parkinsonism-vs-parkinsons-whats-the-difference

Parkinson’s Disease and Parkinsonism – An Overview | MyParkinsonsTeam

https://www.myparkinsonsteam.com/resources/parkinsons-disease-and-parkinsonism-an-overview