Sorry to hear! Yes you've seen a doctor. Postural hypotension
or orthostatic hypotension
can be caused by:
Medications, or putting some types together,
Heart problems (failure)
Endocrine problems. An underactive thyroid (hypothyroidism
) or overactive thyroid (hyperthyroidism
) can cause low blood pressure.
Dehydration. Even mild dehydration can cause weakness, dizziness and fatigue. Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can all lead to dehydration.
Severe infection (septicemia).
Nutritional deficiencies. A lack of the vitamins B-12 and folate can cause anemia, a condition in which your body doesn't produce enough red blood cells. In addition to making you feel tired because you're not getting enough oxygen, anemia can lead to low blood pressure.
Or the syncope idea sounds descriptive too. You may want to look for a reason. Sometimes even trace mineral imbalances magnesium, etc. for an odd reason or genetic condition can cause syncope etc.
I've found Chinese medicine very effective as well, especially after running into blind alleys everywhere else.