Thank you for your question, and I am sorry to hear about your symptoms. I strongly recommend that you continue to work with your primary care physician
to determine the cause of your symptoms, but here are some general considerations. Although it sounds like the sensation is hard to describe, it would be very helpful to understand the quality (pressure, stabbing, burning, etc.), the tempo (when it starts, how long it lasts), and any alleviating or exacerbating factors. Chest pain can be caused by a variety of organs, including the heart, lungs, esophagus/stomach, and the muscles/bones. Heart-related chest pain is characterized as a crushing pain made worse with exertion, often with associated nausea and sweating. A normal EKG, echo, and your healthy baseline make this less likely. Lung-related causes include pneumonia
and blood clots, both of which would cause shortness of breath. Pneumonia would also cause fever
and cough. The GI system can cause atypical chest pain in the form of acid reflux disease. This should be strongly considered in your case given your age and unrevealing workup thus far. If your symptoms are made worse with lying down or after meals (especially with caffeine, chocolate, peppermint, and/or tomato sauce), this would be more likely. Finally, if you have had a recent viral infection (such as the common cold) and it hurts when you press on your chest, you may have something called costochondritis, which is self-limited and resolves over the course of weeks. Again, there are many possible causes, and I would recommend that you try to note any associations between your activities and symptoms. Please continue to meet with your primary care physician to work through this medical issue. Best of luck!