I've had panic attacks in the past before. Theyre so scary!! The walls around you become restrictive, and your lungs feel empty of air. Its a crazy feeling, thinking that youre out of control and theres nothing you can do. I've found some things do help tho, maybe you could try them out:
Talking to a good friend who relaxes you,
Taking some big, calm deep breaths,
Imagining you are in your favourite spot,
Begin doing something which occupies your mind,

this one has been the best of help:
Scream and yell as loud as you can and get all your feelings, whatever they may be, out!

Good Luck
xx