Welcome to HealthcareMagic.
Does the pain increase on activity ?If so what kind of activity worsens your pain?
As per the symptoms you have can have either a Cardiac abnormality
, Lung disease or an abdominal disease.To rule a weak heart , in case where the primary test turn normal , a stress test
has to be done.In stress test ,, stress is induced on heart by exercise or drug and the heart condition is assessed.
There can be some abdominal condition which present with symptoms like this.
Its unlikely to a carcinoma of lung with no evidence on tests.