Brief Answer: Muscular pain vs GERD.... Detailed Answer: Hi, The pain that changes intensity with change of posture is most likely from acid reflux. Upon lying down as the gravity is nullified undigested and acidic contents of stomach can regurgitate into the food pipe leading to discomfort and pain. This pathology is noted in individuals with acid reflux. Perhaps you suffer from the same. Besides acid reflux, muscular aches and less likely a lung pathology are the other causes of your pain. It is unlikely related to your heart. I would start you on proton pump inhibitor like Pantop D twice a day half an hour before food along with Syp Sucralfate 1tsp thrice a day for two weeks. If it doesn't help you should consult a local doctor and investigated for other causes. Hope this helps. Let me know if you need clarifications. Regards

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