One more thing to consider: his "bowed" chest may be what's called a pectus excavatum, or scooped-out chest. Although by itself it does not typically cause any problems, it can be part of certain connective tissue disorders, genetic syndromes that can have several different connected findings. Mitral valve prolapse can be another one. It may be worthwhile in your son's case to have him seen by a pediatric cardiologist anyway, and raise the question of connective tissue disorders during the evaluation.
Dear Paula,
Although pain can be seen in some patients as a conversion disorder, in which it is more of a psychiatric cause, sharp chest pain is frequently seen in adolescents, and can be seen in some younger children, as well. Of note, the heart is the least likely cause of chest pain in the pediatric and adolescent population. I don’t have enough information to say for sure if your son’s chest pain is benign, or not. However, if it is brief, sharp, usually hurts worse with breathing in, and spontaneously resolves, it is likely to be typical chest wall pain. It has no known cause, but we know that it is benign. His height and weight appear to be appropriate for his age and gender. The pallor and dark circles may be associated with inadequate sleep or with chronic allergies, so you may want to look into this more. Unfortunately, many emergency department physicians who do not typically treat pediatric patients are not used to managing pediatric chest pain. Overall, your primary care provider should be able to assess whether this is benign, or not. If you are not able to get a reasonable answer for this, then consider a pediatric cardiology evaluation.
Finally, mitral valve prolapse does not cause chest pain unless there is significant mitral valve regurgitation associated with it that is also causing decreased cardiac pump function.