What Causes Chest Pain Upon Exertion?
It's an anxiety
Detailed Answer:
Hello,
I guess there is chest pains especially on exertion or shortness of breath. Since you already ran a marathon without any chest pain or other symptoms, less likely to any significant heart disease.
it's an entirely a psychological issue, anxiety episodes. There is nothing to worry about.
whenever one gets excited then there is activation of sympathetic system which leads to forceful and faster heart beat which leads to your symptoms.
You can get one ecg, hemoglobin and thyroid test done just to rule out other causes for this. In treatment part, you should try relaxation techniques like deep breathing, yoga. If doesn't help, then you can get some antianxiety medicine like tab ciplar LA 20 mg once a day prescribed for your anxiety from local doctor.