Both of my kids were severe asthmatics and both of them were triggered by completely different items as well as reacted differently during an attack. You need to see a specialist and ask that your child be tested.
The allergist and the pulmologist will test the lung function and get a "peak flow". These numbers are vital. This tells how well one is breathing and how many milliliters of air is flowing in out of the lungs. From the optimum level the doctor will tell you where the numbers are for you to call for additional medication, go to the hospital or not to worry at all. (Green, yellow and red zones) . Your child will learn to feel these numbers. It also removes a great deal emotion from the event. An asthma attack is scary for anyone. It feels, as my kids used to say, like an elephant is sitting on your chest and you can't breathe. This reaction can be a cough similar to a seal bark, a hacking dry cough or a wheeze. Many more people, not just kids are being diagnosed today than ever before, but know that while it is dangerous, it is controllable. Some scientists are linking it to the environment, while others believe we can just diagonis it better.
Swimming is a great way to strengthen the lungs, and knowing what triggers symptoms is a huge part of the battle. Many of the medications used today do not cause nearly the side effects that we had to deal with 20 years ago. One final note, corticosteriods are often used to treat inflamation of the bronchial tubes. Don't confuse these with the "bad steriods". Treating the inflamation is extremely important, not just treating the cough. It is the inflamation that causes the cough in asthma.
The American Lung Association has great programs for kids and their parents in understanding and living with asthma.
Your first step is to find a good doctor and get the right treatment for you.
BTW, both the kids have been on Singulair for years - one since she was 6 and we haven't had that issue. I do know when you can't breathe, you feel really yucky. Headaches, fatigue and so forth.
I will be keeping you in my thoughts.
S.