cold air, cold water, or an ice pack on you forehead or neck can slow it down before it gets too bad. Take calming breaths. When I feel faint, I lie on the floor with my feet up. I try to remind myself that although I am acting very frightened, I am safe, and that the feeling will pass. I try to remember that I'm going through a difficult stage in life, but that I will adjust and overcome. Every new feeling of a panic attack scared me, which made the panic attack worse. Breathing, temperature change, reassuring thoughts, getting in a safe position to recover are the things that help me. Also, try to embrace something that comforts you, a memory, a picture, a pet, person, pillow, etc.
I'm sorry you are dealing with this! In my experience, they get shorter and less intense after you've worked through the thoughts/feelings that are causing them. Shortly after you've experienced the worst of them, notice how you can feel quite normal again (although unhappy you're having panic attacks).