Please be aware of the risks involved with Singulair and prednisone.
http://www.fda.gov/medwatch/SAFETY/1998/singul.htm
From your description, it appears that you have severe persistent asthma with a significant infectious component during the past year. There is strong evidence that respiratory viruses, especially rhinovirus in adults, account for up to 80 to 85% of acute exacerbations. Numerous anti-viral therapies have been investigated during the past 20 years either without much success and/or with troublesome side-effects.
Infection with atypical bacteria, specifically Chlamydia and Mycoplasma, has also been associated with a small percentage of people with difficult to treat asthma. There are reports of response to treatment of these individuals, with macrolide antibiotics, such as clarithromycin.
Another therapeutic option is anti-IgE therapy, called Xolair® (omalizumab), for highly allergic individuals with high levels of serum IgE.
Immunotherapy, commonly called allergy shots, can also be helpful for people shown to be highly allergic to common allergens. Sublingual immunotherapy (SLIT), which is allergy drops under the tongue, has been used effectively in Europe and is now being studied in many centers in the U.S. Specifically, there have been studies of SLIT for individuals seasonally allergic to birch tree pollen that show significant improvement in lung function during the pollen season.
Finally, from your description, you could have an allergy to the fungus, Aspergilla, called Allergic Bronchopulmonary Aspergillosis (ABPA) that can cause bronchiectasis. The standard treatment for this is oral steroids, but there are recent reports that this condition may respond to treatment with anti-IgE and to anti-fungal agents. There are recent reports also that this condition can result in a sub-optimal response to asthma therapy.
Bottom line is that new treatments for difficult to control asthma are being investigated at many research centers. You may wish to seek consultation at one of these, such as the National Jewish Medical and Research Center or Johns Hopkins University Medical Center.
You really need some treatment by a facility that specializes in the treatment of asthmatics. Mucus production must be evaluated and should be cultured, although they rarely do this. If the mucus colored and if so what color? Ocasionally fungal infections are the cause of the problem. At this point you have what is called a "chronic" problem which has been ignored by your health care provider. In an asthmatic attack the body has an immune system that responds dramatically to the presence of a "non-self substance", commonly called an antigen. This triggers a fil;m of mucus which can be very thick and interferes with the transfer of oxygen between the air drawn into the lungs through the trachea and the blood vessels within the alveoli. Steroids reduce the inflammation and generally an expectorant is required to get the mucus plugs out. You need to buy some current books on asthma or contact an asthmatic group and evaluate your living circumstandes to determine what the antigens are. You may have to throw out all your rugs, spray the walls with ammonia to kill mold and repain and get an electrostatic dust precipator. You may have a home so toxic (or a workplace) you have to move. An asthmatic attack is extremely frightening and often taken too licghtly by physicians, emergency room personnel and ambulance EMT's. Keep albuterol handy. As you know, in a short time you can "fall off the cliff". There are a variety of asthmatic strategies, too complex to loist ina post, but they are available in the literature. Go to MEDLINE and do a search. Good luck.
It is not a good idea to be on prednisone for long periods. I know that prednisone is often the only medication that enables you to breath, but look about removing the antigens from your home and all of the non-self substances that precipate an attack. Those darned infections become established and encapsulated and are pretty hard to kill once they become established in the lungs. You need to have the lung infection cultured. There is a treatment not available in the United States developed in Georgia. This is to utilize phages to destroy the infection. Phage therapy for infections is not recognized by the AMA or the FDA, but it has been around for 75 years and works. It is best for intestinal infections, but can be used in an aerosol for lung infections quite effectively. Phage therapy is an alternative to antibiotics. The phages feed on the bacteria. I am hesitant to tell you where you can get this therapy. You will have to find a physician on your own. The big problem with continual use of prednisone is the development of malignancies. Low-dose aerosolized lung sprays deliver a lower dose and are safer. Yoy need to use an expectorant to remove the mucus films from the lin addition to albuterol and steroids. Good luck.