What Causes Chest Pain After Physical Exertion?

My son went skiing a week ago, returned and exerted himself playing basketball. (he is 23). He also recently re-started taking a drug similar to adderall. He is now complaining of chest pains and describes them as dull, constant ache and tender to the touch. He has Aetna health insurance but cannot find a doc that is open today. what do you recommend.