Hello! Thank you for asking on HCM! I read your question carefully and understand your concern. Did you measure your blood pressure during this episode? Nose bleeding is commonly caused by uncontrolled high blood pressure. A wide differential diagnosis between different disorders affecting the mediastinal structures should be done: - A costochondritis, would cause similar pain, modulated by respiratory movements. But would not explain the bleeding nose. The pain modulated by body position or respiratory movements is usually musculo-skeletal. - an aorta dissection, but this would not explain the pain modulation with respiratory movements. - your symptoms don t seem to be cardiac related, as it is very atypical for the cardiac pain to be modulated from respiratory movements. I recommend consulting with the GP for a careful physical examination and performing some tests like : a chest x ray, resting ECG, routine blood test, kidney and liver function tests, blood electrolytes, thyroid hormone levels, to establish the possible cause. Meanwhile I advise to closely monitor your blood pressure. Hope to have been of help! Best wishes, Dr. Iliri