My son is 32 years old and has been experiencing rapid heart beat, sweaty palms, upset stomach and near passing out since November. He has had EKG s electro cardiogram, CAT scan stress tests, blood work etc and nothing has been found. Blood pressure, glucose levels etc all good. After passing out at work today he was sent to the ER and tested again with nothing found but referred to a nero cardio specialist. What can be causing this? Thank you