Virginia,
From a lot of inferences in articles I've read and from personal experience there seems to be a linkage between fluctuating blood pressure, yeast infection, episodic chronic fatigue, and carbo metabolism (diabetes/hypoglycemia, alcohol abuse, weight disorders), with depression and possibly epileptiform seizures. If any of these other conditions apply, it maybe hard to sort it all out, but at least have them check for unusual Candida presence. Memory effects may be part of the mix as well, but memory flaws, and emotional over-reaction to them, may also be also be age-related.
I can't remember why...but I worry about it.
But bear in mind that overall though low bp is generally regarded as a blessing, it ain't necessarily so.
Be well!
Darrel