Panic is fear, just like anxiety is fear.
An idea enters your mind that frightens you and when we feel fear, adrenalin is activated. The increased adrenalin causes the pounding heart, breathlessness, jittery feeling.
It doesn't have to be a huge fear, just fear.
Fear of failure, of losing (perceived) control, fear of success (and what comes next), fear of adulthood, more concrete fears like fear of persons who have hurt us...
Even tantrums can be fear making us behave in a way pushes things or people away from us, or us away from them. A self-protective behavior.

What begins the process of the anxiety and panic is key. If you can notice when the anxiety and panic begins, see if you can also notice what you are thinking which may tell you what causes your fear. It takes practice, and some journalling may help because it can free the mental process. Just write whatever comes to mind.