I feel like I am having GERD (as also confirmed by a doctor), so due to acid reflux, I have started experiencing heart burns each night and unable to sleep since last week. But, the pain is not in middle of chest, pain is at very left side below armpit on chest muscles. How do I know if this is really heart burn or symptoms of a cardiac problem? I am a good lover so regularly consume restaurant food (twice a week). And my weight is 103 kgs and live a sedentary life since last many years. moreover I am unable to start excercising as I have ACL/meniscus tear in left knee.