What a mystery Mike
I do hope you can find the cause, it is always easier to deal with something if the aetiology is known.
I have developed generalised myoclonic seizures in the last 12 months, sometimes with momentary Loss of consciousness.
EEG only abnormal at the time of a seizure, however I have some "white degeneration " of brain tissue on MRI.
I wonder if there is a similarity?
Good luck with finding th answer.