Thanks to all who responded, I appreciate your concern, especially Ron 
Hoggan, who pointed me to a probable cause.

It looks like a transient ischemic attack, caused by foolish indulgence 
in Christmas dinner with resultant high blood sugar. This in a person 
who has always had problems with blood sugar, and has been very low to 
zero carb for months.
There has already been some improvement, and the future is promising 
according to medical websites.

William