Thanks for choosing health care magic for posting your query.
Yes, it can be anxiety
. Especially as ECG has come normal.
You could get a stress test
done and also an echo. If these results are also normal and as you have said that you got symptoms during a stressful period then in that case , it could very well be anxiety.
You should visit a psychiatrist
who can assess your mental state and will be in a better position to comment on your diagnosis.
Cognitive behavioral therapy
are certain drugs that can be useful for you.
Hope I am able to solve your concerns.