Hello! Welcome on HCM! I understand your concern and would explain that his symptoms could be related to an electrolyte imbalance or cardiac arrhythmia. A vertebro-basilar insufficiency (low blood flow supply to the brain, related to the narrowed cervical arteries) or an inner ear disorder can not be excluded either. Does he have neck pain? Chronic degeneration of the cervical spine can mimic this clinical scenario. Anyway, the situation is not so emergent and it can wait until consulting with your attending physician. I would recommend performing some tests: - a cervical spine X ray study - a Doppler ultrasound of the cervical arteries - blood electrolytes. If the problem persists, consulting with an ENT specialist may be necessary. Hope you will find this answer helpful! Wishing good health, Dr. Iliri