If I fall asleep on my left side and stay there, I will wake up with left sided chest pain. This is the only way to have the pain. It hurts on the inside, not to the touch.  It will last up to two hours but subside. I have already been to a cardiologist with no results. It has been happening for ten years and nothing is helping.
Thanks for your question on Chat Doctor. I can understand your concern. Since your chest pain is associated with specific position (left sided sleeping), possibility of musculoskeletal pain is more. No need to worry about heart diseases as your reports are normal. So apply warm water pad on affected areas. Take simple painkiller and muscle relaxant Chat Doctor.  Wear chest belt. Avoid movements causing pain. Avoid sudden jerky movements. Don't worry, you will be alright with all these. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.