Thanks for your question on Health Care Magic.
I can understand your situation and problem.
Left sided
chest pain, tightness along with breathlessness are seen commonly with heart diseases.
So first get done ecg and 2d echo.
If both are normal than no need to worry for cardiac diseases.
Sometimes
stress and
anxiety can cause similar symptoms. So
consult psychiatrist and get done counseling sessions.
Try to identify stressor in your life and start working on its solution.
Don't worry, you will be alright.
Avoid stress and tension, be relax and calm.
But first rule out cardiac cause.
Hope I have solved your query. Wish you good health. Thanks.