Hello! Welcome and thank you for asking on HCM! I read carefully your question and understand your concern. Your blood pressure values are below the normal ranges. There are many causes of low blood pressure and some investigations need to be done. Besides, your past medical history for breast cancer is really concerning, and a careful check up is necessary. I recommend you to consult with your GP for a careful physical examination and some tests: -resting ECG and a cardiac ultrasound to examine the cardiac function and structure (to rule out possible heart failure) -chest x ray study -abdominal ultrasound -blood lab tests (complete blood count, PCR, sedimentation rate, kidney and liver function tests, blood electrolytes, fasting glucose, vitamin B12 levels, etc). A head up tilt tests is necessary to exclude possible orthostatic hypotension. You should discuss with your doctor on the above mentioned issues. Meanwhile, I recommend taking plenty of fluids (water, juices) and increase the salt intake with food. Hope to have been helpful! Greetings! Dr. Iliri