I was diagnosed with exercise induced asthma back in 1999 after having an attack at the end of a 15k race (running). Having been there, I know how scary the feeling can be when the attack happens.
You need to see a doctor.
I went and saw a doctor, they gave me a prescription for an inhaler. In my case, there are a few triggers: cold temps (as was the case with that 15k), or my seasonal allergies (oak pollen, yay me).
You need to see a doctor.
Luckily, I haven't had more than two or three attacks that I can recall since that one incident. And I don't really think about my exercise induced asthma anymore; I now only use an inhaler when my allergies are kicking or when it's extremely cold.
You need to see a doctor.
However, all the advice and other anecdotes that you'll read here on BF are pretty much useless, because those anecdotes are for each individual poster. My exercise induced asthma may be different from your asthma attack.
The bottom line?
You need to see a doctor.
(preferably an asthma specialist)