Lightheadedness and Chest Tightness.

I have been having on and off breathlessness but my oxygen levels are intact at 97-98. I have had my ECG 4 days back and negative Troponin I level on 15th when I was rushed to emergency. I have been to ER many times with chest pains and rapid heartbeats but came up with only sinus tachycardia. My coronary angiography was done 5 months back which came normal and 2D echo was done a week back which was normal but for last 4-5 days I'm feeling on and off breathlessness and chest tightness and lightheadedness. I take metoprolol and olimsartan. Dr has also put me on opiprimol and clonzaplam. Cab these anti depressant cause lightheadedness? My BP today was around 113/75 and normal HR of 75. Is there something still missing in Cardiac evaluation which is causing these symptoms?