Hello,
Left-sided chest pain can have several causes like Costochondritis, Tietze’s syndrome,
Fibromyalgia, Heart disease,
Heartburn or Gastroesophageal reflux,
and Anxiety.
He can take pain relievers like Ibuprofen or Diclofenac. However, I would still suggest that you seek consult with a Doctor to exclude more serious causes of chest pain. Your Doctor would examine him and request for several tests like blood tests, Chest x-ray, EKG, and Echocardiogram.