Hello Good Evening,
This might be related to stomach and duodenum
, not to lungs, so nothing to be found on X-ray.
You did not describe about your habits like alcohol or smoking
because you could be suffered from gastric or duodenal ulcers which can present with atypical symptoms also, like you feel, but later on they can convert into burning sensation and pain.
So go for a UGI Endoscopy
to rule out any Gastritis
or duodenal ulcers, but there are strong chances to having these, so you will find definitive diagnosis and treatment.