How acurate are EKG and chest x-ray for diagnosing heart trouble

Hi, I am a 34 year old male and have been having some strange symptoms that my internist and the doctors in the ER  have no answer for. Back in May I began experiencing what I call lightheadedness. It wasn't so bad that I felt like I was going to pass out or fall over but still strange enough for me to worry. With this I have also experienced headache and symptoms closely related to a sinus infection. In the ER I was given an EKG, a chest X ray and blood and urine tests. All of these came back normal. I was given an antibiotic and symptoms seemed to disappear after a few days. The same symptoms came back in August. I again went to the ER and was given the same tests. All normal again. The same symptoms have now returned. I am experiencing lightheadedness, mild shortness of breath, fatigue, mild discomfort when I inhale deeply, and an occasional wheeze when I breathe. Given the fact that in the last six months i have had three EKG's, three chest X-rays, and three blood tests is it safe to say this is not heart related? Any idea which direction to head in as far as a definitive answer? The only answer I have gotten so far is allergies. Thanks for your time.

[Mukesh Garg, MD]

It is encouraging that your tests including EKG and xrays are normal. If your doctors feel necessary they may want to do an Echocardiogram to confirm normal cardiac structure and function