Did the cardiologists do a complete workup, echo, EKG, stress test, ct, and holster monitor to rule out cardiac?
Her symptoms sound like pots but it is important to make sure heart is sound
My heart runs 69 to 90 during day
90 to 150 standing
At night can run in low 60's and high 50's
Find a cardiologist or neurologist that is trained in autonomic dysfunction Google it in your area and get her in
Any questions ask will do my best to answer