hi welcome to Health care magic forum. You are 15 years old , you had spells of heart stopping, compressed, struggle breathing of short spells. You had it only 20 times in a span of 7 years.
In this age getting such symptoms suggest of anaemia
, gastric hyperacidity
, or psychological effect. Of course cardiac involve ment also will be like this in some cases but it is continupous, now after reading this you may feel that you are getting it continuously now. it is a syndrome by reading the symptoms.
I advise you to consult a physician for diagnosis and treatment, in this way you can have diagnosis, and exclude the cardiac involvement.
Dont worry you will be fine soon, and thanks for calling.