You seem to know a lot but not about your body and its functions
You know what is palpitation
and don't know why it is coming.
Palpitation, sweating, trembling, goose bumps etc are symptoms related to fear.
They come when adrenaline
Normal procedure when human beings fear.
Understand the body mechanism logically and you can win over anxiety
Again health conscious people have this kind of problem.
Immediately consult a qualified counselor (not psychiatrist
Wish you good future.