Hello! Thank you for asking on HCM! I think that your friends problems may be related to different disorders like : - an inner ear problem or vestibular neuronitis -a viral infection or gastroenteritis - dehydratation - brain hemorrhage - epileptic seizures - anxiety I would like to know if he has any other symptoms like dizziness or spinning, gait disorders, headache, fever or diarrhea. I would recommend some tests like : a routine blood tests for anemia or inflammation, labyrinthine tests, blood pressure monitoring, blood electrolytes, kidney and liver function tests, Head Up tilt test for orthostatic hypotension, urine analysis, chest xray, ECG, EEG and possibly a brain CT scan, to establish the cause. Hope to have been helpful! Greetings!Dr. Aida