Hello! Thank you for the query. Such pain is usually caused by rib nerves irritation (intercostal neuralgia) due to inflammation or nerves compression. It is characteristic for this condition that the pain is sharp, well localized, aggravates when breathing. But there are several diseases that should be ruled out before such diagnose. If there was any chest trauma recently (even not significant for you) there might be a rib fracture. If your pain has appeared suddenly, there is always a risk of pneumothorax (if there was no trauma, spontaneous is possible). With it also shortness of breath appears. Every chest pain, especially radiating to the left scapula, should be checked with heart condition. When you do breath in, the liver is moving, in some cases gallstones can give such symptoms. In some cases such musculoskeletal pains and nerves pains can be caused by ions deficiency (especially Magnesium and Potassium). It is advisable for you to have ribs X-ray (if there was any trauma), chest X-ray, heart ECG, abdominal ultrasound and ions blood level. If all mentioned disease will be ruled out, you should try non-steroidal anti-inflammatory drug. Ibuprophen is one of them but has medium muscles and joints penetration. For such pains better medicine is Diclophenac. Hope this will help. Regards.