My 17 Year Old Daughter Has Been Experiencing Periodic Times

My 17 year old daughter has been experiencing periodic times of a racing heart, nausea, dizziness, some chest pain and fatigue. We've been to the ER three times already and EKG's, blood work are normal. She is scheduled to be fitted with a 30 day event monitor next week. Meanwhile the symptoms persist and I need to know when or if to go to the ER again or if there is anything else to be done.