Yesterday, after dinner, I sneezed which prompted a very sev

Patient: Yesterday, after dinner, I sneezed which prompted a very severe, uncomfortable pain in my chest, behind my breastbone. That was followed by lightheadedness for 1-2 min and a feeling like I was going to faint. After sitting down for 4-5 min and collecting my breath, I felt fine. I am 28 years old and exercise very regularly. Was this some kind of acid reflux/heartburn or something more serious, like a heart attack?

Doctor: