Thanks for your question on Health Care Magic.
I can understand your concern.
No need to worry for cancer as cancer is extremely uncommon at your age of 21 years.
Your ecg is also normal, so no need to worry for cardiac disease as well.
In my opinion, you are mostly having
stress and
anxiety related symptoms.
So better to
consult psychiatrist and get done counseling sessions.
Try to identify stressor in your life and start working on its solution.
You may need anxiolytic drugs too.
So avoid stress and tension, be relax and calm.
You are not having cancer or cardiac diseases.
Don't worry, you will be alright.
Hope I have solved your query.
Wish you good health.
Thanks.