In her 90s mgm had some shaking and difficulty walking. Very old gp gave her dopa without diagnosis. She never had Parkinson's but med side effects. Y?

Depends. It is not uncommon to try and treat tremors in the elderly with parkinson disease meds. Parkinson's is a very complex disorder with a variety of subtypes and the book is constantly being rewritten. Essentialy tremor is best treated with beta blockers usually, but in an elderly person a trial of Dopamine agonists might be tried, then stopped if side effects or other issues develop.