Hello!
Welcome and thank you for asking on HCM!
I passed carefully through your question and would explain that besides the clinical symptomatology (headache triggered by sitting or standing up),
intracranial hypotension is associated to specific changes in the brain and spine
MRI studies.
So, if your brain and spine MRI study are normal, we can exclude this possibility.
Besides, this disorder is not usually treated with
fludrocortisone. The main treatments are prolonged
bed rest or epidural blood patch.
Another disorder, which may mimic this clinical scenario, is
orthostatic hypotension, which is usually treated with fludocortisone.
For this reason, I recommend performing a Head Up Tilt test to investigate for this disorder.
You should discuss with your doctor on the above tests.
Hope you will find this answer helpful!
Kind regards,
Dr. Iliri