Go to the hospital and get it checked out ASAP!! Chest pain with left arm pain is the most classic symptom of a cardiac issue such as an MI (heart attack). If you’re a bit on the older side, with a history of poor diet, it’s likely you’ve got some blockages in your heart that may need medical attention. Ultimately, fasting will probably help as you’ll quickly lose weight which is good for your heart. But if the blockage is severe enough, you might just need some medical intervention before you cause any serious damage to the heart tissues.