I know exactly how you're feeling. I've had panic attacks and anxiety for over ten years, and if I have a particularly intense panic attack, or if I start worrying and freaking out while I'm having a panic attack it gets worse and lasts longer. I've felt that I'm gonna pass out before, too, but it's never happened, in all the ten years I've experienced this lovely thing we call anxiety. The best thing that has helped me with my anxiety in general is cognitive behavioral therapy. The best thing that helps me during an anxiety attack is to acknowledge the feelings I'm having and let them wash over me and remain as calm as possible, telling myself that I'm having a panic attack, and to just allow my body to experience the sensations. If I just let it happen and don't freak out or fight it off, even though it's very unpleasant, the length and severity of the panic attack is diminished and shortened. The more you try to fight it or the more scared you get during the attack, the more intense and the longer the attack will be, at least in my experience.
I've also found that if I'm not taking care of myself by not eating right, not getting enough sleep, not exercising, my anxiety is much worse. If you can find doing something you really enjoy, spend more time doing whatever that is...it truly helps.
This acronym is the best thing I ever learned in cognitive behavioral therapy:
G stands for be Gentle With Yourself. You're doing the best you can with the hand you've been dealt. Eliminate the negative self talk, and don't beat yourself up.
R stands for Relaxation. Practice meditation, guided meditation, or mindfulness. This helps bring you back to center and gets your mind off your anxiety and your symptoms.
A stands for Accomplishment. Do something every day that you consider an accomplishment, even if that's only to get up and take a shower and brush your teeth if it's a bad day.
P stands for Pleasure. Do something you really enjoy..reading, listening to your favorite book, spending time in nature, watching a movie, or doing whatever it is you love.
E stands for exercise. Do something every day for at least 30 minutes. Even if that's taking a brisk walk around your neighborhood or a nearby park.
S stands for Socialize. Try to get with a friend or get out and do something where you're around people so you don't isolate yourself. Isolation can make things worse.
Do you GRAPES weekly! It's an integral part of our mental health and is a loving thing to do to take care of yourself.
I hope you feel better soon. Hang in there!