Possibly it is related to acidity. I would start you on antacid
20 mg twice a day for few days and see how you feel. This is available over the counter as prilosec
Besides medication, it would be worthwhile getting an x ray of chest, an abdominal ultrasound
and ECG in view of your lung shadow. Also look if there are any tiny vesicles over the chest wall as it may suggest an viral (herpes infection). You can plan these test under your physician's guidance as you start those medicines.
Hope this answers your query.
Wish you a speedy recovery.