Ever since I stupidly had my tonsils taken out, everything goes to my lungs. Ugh.
Since you've got the western medicine side covered, you might look to alternatives that will pump your immune system up (and properly, since allergies mean that your body is reacting inappropriately to things that aren't poisons...the immune system is behaving inappropriately (if only we could discipline our immune systems!)). I am sure that you know that the steroids are *depressing* your immune system...that's how they work. They falsely stop the body from reacting to something the body feels is a problem. (I have a friend giving her daughter something like 3 steroids, and says on FB "hopefully these will kick the butt of her asthma!"...yeah, they aren't kicking anything's butt but her immune system, but I digress)
So...diet absolutely (I have to go entirely 100% dairy free, which means going down to milk solds, whey, caseinate, EVERYTHING has to be gone, to be entirely allergy-free), acupuncture, chiropractic, homeopathy.... Find the root of the cause, instead of just throwing body-depressants at it. If you're just covering up the symptoms (steroids, cough syrups, etc etc) you're not getting to the problem. You're just ignoring the problem b/c you aren't feeling the symptoms.
Right now we've had the creeping crud (the one that is like a moderate cold that makes you feel like someone is punching you in the face...a bunch of people I know have had it...some thought it was allergies until they found out that others have had it, some who don't tend to get allergies), and it's sitting on my lungs right now, and I've had some low-level asthma... Things that are working for me (besides upping my chiro visits, which is doing amazing things but take time) are small amounts of black coffee (an amazing medicine!) at the beginning of the wheezing...also nettle tea at the beginning (it tastes worse than black coffee to me, so I'm only using it if it happens at night when I need to sleep). Using "mullein" has been recommended to me (by a fellow former asthma sufferer..had it from 5 well into adulthood, starting with the alternative stuff, and he hasn't needed an inhaler for years now) so I'll get some of that when I can!
Best of luck!