What Causes Lethargy, Chest Pain, Dizziness And Fainting In Children?

,Hello, my son is 7 years, for the past month, he is feeling very lithargic, he complains of onset chest pain, he points exactly to his left side where the heart is, with an immediate set on of severe dizziness that is getting worse, last night he fainted in my arms, right after he told me that his heart was hurting him. He is weak at times and even the teachers have noticed a difference in him. Please let me know what this can be and what do you consult me to do.