Welcome to Health Care Magic
D-Dimer test is a test for Pulmonary Embolism
, it is used to detect any thrombosis
. When test comes negative it means that PE or thrombosis is ruled out, but a positive test does not mean that person is having PE, false positive results are there, so other tests and clinical evaluation is done to fix the diagnosis.
As your other tests like ECG, blood tests, ECHO, stress tests are normal so as per my opinion every thing is normal.
The mild pain, light headedness, shortness of breath
etc may be due to Anxiety of having PE. Anxiety may present with sweating, chocking sensation in throat, chest, breathlessness, dizziness
, butterfly sensation in stomach etc. and these symptoms are mistaken for any cardiac pathology. So most likely its Anxiety.
Both medical and non medicinal treatment are available for anxiety and with good results, kindly visit a good psychiatrist
for expert opinion.