My Daughter Is 17 Years Old. In The Last Week

My daughter is 17 years old. In the last week she has started reporting intermittent substernal chest pain. It does not radiate, she is not dizzy or SOB. she does complain of a headache and fatigue during the episodes which last up to several hours. I have given her Ranitidine for the last 2 days and it has not helped. She has not tried the tums yet. She has been under a lot of stress in the last 2 weeks and I am wondering if this is it or should I have her checked for an arrhythmia or something else. Any ideas?