My son is 13 years old, since 2 years, at least 2 to 3 times in a day his face, chest, and ears become red and after 10 to fifteen minutes become ok

Flushing: This sound like flushing, which is defined as turning red for a variety of physiologic reasons. Flushing can be triggered by emotions, fevers, infections, drugs, etc.. Since your son has had this most of his life (and i assume he's otherwise fine), it is likely emotional and harmless. If he is not otherwise fine, further evaluation by a doctor will help.