Hello Sheena! Thank you for asking on HCM! Regarding your concern, I would agree with ER doctor for excluding a cardiac related option of your pain. Your pain doesn t look like being of cardiac origin (facing pain nature and characteristics of breath and position relations). But, it is necessary to exclude other possible causes, like pericarditis (a careful physical exam, cardiac ultrasound); backbone degenerative process (a careful physical exam, backbone X ray study, CT or MRI); pleural inflammation (pulmonary auscultation, chest imagine studies), etc. I recommend you to consult with an internist for a comprehensive differential diagnosis work up, to identify the right source of your complain. Hope to have been helpful! Greetings! Dr. iliri