Hello! Thank you for asking on HCM! I read your question carefully and understand your concern. Your symptoms seem to be caused by orthostatic hypotension, which means that your blood pressure falls during standing up from sitting position. This may be an adverse effect of the antyhypertensive therapy you are taking. So some changes in your therapy may be necessary. I recommend consulting with your attending physician and measure your blood pressure in sitting and standing up position. In case of a decrease more than 20mm Hg of systolic blood pressure during standing up, this would be in favor of the diagnosis of orthostatic hypotension. A head up tilt test is needed to determine this diagnosis. Hope to have been helpful! Greetings! Dr. Aida