I feel for you. I know what it is like to feel at your wits end. My son has been battling with this disease since he was 15 months old. He has been on all different kinds of meds. Some help and some don't. I think key is to find out what she is allergic to. If it is something that can removed from her day to day life that would be best. My son is allergic to cats and certain pollens. We can kick the cat outside but getting rid of exposure to pollen is impossible, especially with an active boy and were I live. Her triggers may not be related an allergine but maybe weather or changes in or viral. There also may be a possiblity she may be reacting to a food allergy like with milk products (and there is milk in a lot of things). You may also be able to treat her asthma with a natural supplement. My son has been on a natural supplement for a few months now and it has helped him tremendously. He used to take Singular and Advair and would still need his inhaler or nebulizer now we have him down to just the Advair and rarely needs his inhaler.
We have had experiences with a few different doctor over the years and it seem like most don't really know what to do either. They seem to just say, "try this, and this and this" unitl you are going home with about 5 different perscriptions. I have even convinced some doctors to give me something because I wanted to try it but they didn't have any good reason really to let me try it. So my advise to you would be to find a specialist in the field of respirartoy problems and find out what they think and then go and research things for yourself. Go to a health food store and ask questions, a dietichian and ask questions or research this on the internet. Don't just settle with what the doctors say because I don't really think they don't have it all figured out. Anyway, that is my opinion you can take it or leave it :o). My prayers go with you!