Hello and Welcome to Ask A Doctor service. I have reviewed your query and here is my advice. Chest pain might be related to many health problems. To make a differential diagnosis is always important because it might be caused by heart problems that need immediate treatment, but it might also be related to pleuro-pulmonary problems or neuromuscular damage. Considering the fact that the pain gets worse when you cough, take a deep breath or yawn in my opinion it might be related to a temporary neuromuscular problem. It is necessary to perform a physical examination of the lungs or a X-ray to determine if it is a pleural inflammation, but this usually happens after a lung infection and you didn t mention to have had any episode of cough for some weeks. However since the pain has improved, you can try using anti inflammatory drug (Naproxen) for some days, and if you don t improve you should go to consult a doctor. Hope I have answered your query. Let me know if I can assist you further.