Referring to the symptoms you reported (burning sensation in the chest that is also present in the left shoulder and is related meals), it seems possible that you might be experiencing gastroesophageal reflux disease. Gastroesophageal reflux disease is a condition in which the gastric acid enters back up the esophagus where it might cause inflammation of the mucosa. This inflammation is presented with pain in the chest or in the back.


Incompetence of the lower esophageal sphincter, transient lower esophageal sphincter relaxation, impaired expulsion of gastric reflux from the esophagus, or a hiatal hernia might be the causes for gastroesophageal reflux disease.


You might want to visit a specialist for the upper gastrointestinal tract for a physical examination. Gastroscopy might be recommended to visualize and to diagnose or to rule out the mentioned condition.


Meanwhile, avoiding substances that might act as irritants to the esophageal mucosa (alcohol, caffeine, etc.) might reduce the inflammation and ease the symptoms. Lifestyle modifications (avoiding stress and anxiety, practicing relaxation techniques) might be helpful, too.


As for the light flashes you might visit a neurologist for further examination because the symptom is not specific enough for any diagnosis to be given.