dear sir/ Ma'm
thanks for writing to us.
A pain which is in mid chest and comes always on exertion and relieves by rest is likely to be anginal or cardiac or heart pain. But if the pain comes suddenly, comes as a sudden very sharp pain
, lasts for less than a minute, can be elicited by touch or pressure, does not comes up on exercise/running/exertion, it is more likely to be non-cardiac (non-anginal). Moreover since your TMT & cardiac USG is ok the probability of having a real significant problem is low. i agree with your cardiologist's advise. Relax. get your stress
nuclear test done. and discuss with your cardiologist.