I've been dealing with anxiety attacks for 3 weeks now. Basically all i do is starting to take 5 deep breaths into the nose and out the mouth, when i am a little bit calmer, i grab anything that i find to put my emotions into a piece of paper, not perfect or studied sketches, literally a big amount of random shapes, lines and so on WHATEVER i feel to put on that sheet of cheap paper, usinf different colors and i noticed that after that i feel way better.
Probably because you express yourself and let it all go in creative way.
Another thing, and this might sound weird at first: imagine the detail of your fingertips. Visualize any centimeter of your body in a state of calm and you could feel better, to me it helps to do this and think "hah, my mind is so busy with anxiety but nothing's really happening outside of that, my body is still." and this calms me down!
Another way: Run. Start randomly running outiside or in your house too if the space it's not too narrow and free your body.
Similiar to this, dance without music, even while you're sitting, again, just to express yourself and feel connected with your current emotions.
The thing is this: you can't calm down if you are not in touch with your inner feelings, i'm not saying that you must know what scares you in the moment, but just listening and usually any method that lead to express yourself is a good tool to do so.
Otherwise you can try with meditation and small midfulness exercises as well!
(I don't know, i have your same problems, following these steps sometimes helps me, sometimes no and i just take some drops of a tranquilizer, but hey it's really hard to snap out of panick attacks when you're alone, don't blame yourself for not being in control, it's normal. We always beed support from a therapist or friend or family, we can't get out of a dark and heavy situation completely alone, otherwise we wouldn't have fallen into that in the first place. Hope you'll feel better soon, pal! Don't worry, it's okay to not being okay sometimes )