My asthma is very mild and 100% allergic, but Singulair has been just wonderful for me.

Another trick (that you probably already know) is that when your chest gets tight, focus on the exhale and use your accessory muscles to force air out. Asthma actually prevents you from exhaling fully - the reason you feel like you can't inhale is that your lungs are already full of spent air. That won't help in a full-on asthma attack, obviously.

Good luck - hope you get it sorted.