welcome to health care magic
Your symptoms could be due to-
1) Cardiac (Heart) pathology
Since you have undergone all tests 4 yrs back, you have to consult a general physician and get all tests again as you are overweight
also which is one of the risk factor for heart disease
. Once you rule out any medical cause, it is just the anxiety which is bothering you for which get psychiatric consultation.
Till then don't panic and try relaxation exercises like Deep Breathing, yoga or meditation
which will help you