I use just the cs in my nebulizer. I was going to get the lobelia extract but the cs did just fine on it's own. I make my own because I need a lot of it for my cats. A health food store would carry it. I make mine at 15 ppm.
I don't know if cs would help your asthma since what cs does is kill germs. Put about a tablespoon under your tongue and hold it there as long as you can (minimum 30 seconds), then swallow it. When I have an infection, I do this every 4 hours or so. Many people use cs regularly but I don't...just when I'm infected.
Many say that it helps the immune system, and it sounds like you need that for sure. The steroids wipe out the immune system and set you up to catch everything that goes around. I don't know enough about using cs to boost the immune system to help you but I'll bet someone here can tell you!