Thanks for your question on HCM. In my opinion since you are having left sided chest pain, ECG is must to rule out heart disease. If this is normal than I suggest you to get done chest x ray. As many times pleurisy ( inflammation of pleura) can cause similar chest pain. And common causes of pleurisy are 1. Pneumonia 2. Pleural effusion. And both of the above can be easily diagnosed by chest x ray. Pain of diaphragm can be reffered to shoulder. So diaphragm irritation may be the cause for shoulder pain. If all above investigation s are normal than it might be muscular pain.