What Causes Dizziness,dimencia,light Headededness And Shortness Of Breathe?

my daughter is 14.5 yrs old. 5'6" 150 lbs but not fat, she is coordinated but to in great shape, but athletic/plays hard. Recently she has been getting dizzy, dimencia, light headed, then shortness of breathe, (while not doing anything demanding or physical at all) but the first time it happened (after playing kinda of hard) her chest hurt and heart seemed to beat awful fast/hard. Iron and sugar counts have tested out regular. She had her first period at 11.