Stress ECG or Stress ECHO. Comes and go.

Hi doctors, If ECG comes normal then should I go for Stress ECG or Stress ECHO. I have been taking Petril Beta 10, twice daily from the past 4 months for treating Anxiety. But from the last 1 month, I have been experiencing Dizziness and this dizziness increases further when exposed to loud noise or music. I just don't know whats happening wrong with my body. My parents are not taking my symptoms seriously as they have been told by local doctor that it is due to anxiety. At some moments, I also feel breathlessness as if there is lack of oxygen. On June 30, I had ECG ECHO AND STRESS ECG done with some blood tests and doctors said everything is fine. But why after nearly 6.5 months of treatment, I m not completely fine and healthy as I used to be. Please doctors help me diagnose my problem. Also from the last 2 months, i m having dry cough which comes and go. Thank you in advance.