Thanks for your question on Healthcare Magic.
I can understand your concern.
In my opinion, you should definitely
consult cardiologist and get done ecg, 2d echo and
stress test (trade mill test) to rule out heart diseases.
If all these are normal then no need to worry for heart diseases.
Sometimes, undiagnosed stress and
anxiety can also cause similar symptoms in young adults (21 years).
So
consult psychiatrist and get done
counselling sessions. Try to identify stressor in your life and start working on its solution.
You may need anxiolytic drugs too.
Don't worry, you will be alright with all these.
Avoid stress and tension, be relax and calm.
Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.