Safe Substitute for Singulair?

Has anyone who has gone off of Singulair or taken their child off of Singulair been offered or discovered an alternate treatment? My 2 yr. old son has been tested extensively for Allergies/Asthma and the tests reveal that he apparently does not have either condition, however, he does many of the symptoms: chronic cough, sinutis, frequent wheezing, etc. and I do definitely feel that Singulair helped my son's breathing and energy... so I was very relieved to have him on it -- at first. But his severe mood and behavioral changes were enough for me to take him off of it after 4 months. I have absolutely no doubt that for him the drug is not the drug of choice. I would rather sleep in his room every night to monitor his breathing and nebulize him as needed for the rest of my life than to have him on Singulair again. But I do feel as if he still requires treatment, be it a "pill" or procedure or some other medical intervention of sorts. Is there one?? (And, yes, we have allergy-proofed our house: we don't smoke, have no pets, have no carpets, do have an air purifier, etc...)