I'm having this left side chest pain that's been bothering me. I visited a cardiologist, had an echo and ECG done, and everything came back normal. Even my chest X-ray showed no issues. But the pain's still there, and it sometimes gets worse when I walk a long distance. I don't have a cough or any breathing problems. I do have bronchitis asthma, but I'm not experiencing any symptoms from that right now. What could be causing this? It's really concerning. Can you help me figure it out?