thanks dear for writing to us looking at the symptoms me too would have suspected heart rhythm disorder in the first instance but since doctor has already ruled out heart disorder i will look for an alternate diagnosis. i think he is having something wrong with his ear either inflamation of the inner ear or labyrinthitis also i will rule out stroke which is much less common cause but may be present . i recommend you ENT consultation please let me know if this was helpful and do ask for any further queries hope he gets well soon.