Welcome to HCM
With your history it is most likely that you had a episode of focal cunvulsions as it moved up to arm and hope fully subsided itself.
I think you should consult a Neurologist
as this type of convulsions originate from our part of brain known as cerebral cortex
There may be a focus to be examined and followed by EEG and CT Scan/MRI brain in hope to know the cause.
Other possibilities are a form of tetany
caused by low calcium,rest tremors in old age Parkinson's disease,other abnormal movements are chorea
they are quite different.
Do not ignore abnormal movement
Please take care
Good luck to you