Mucous plugs symptoms and conditions

My almost 7 year old son was prescribed Singulair 3 years ago for severe asthma and allergies. It worked great--for a while. No hospitalizations, incidences of bi-lateral mucous plugs and pneumonia decreased, etc. I thought it was a miracle drug for him. This past summer/fall however, the nightmares, sleepless nights, multiple sinus infections, moodiness and mild anxiety, extreme hunger (he can now eat my 6'7" 260 lb. husband under the table and my son only weighs 52 lbs.), thirst, leg pains, reflux and very frequent complaints of stomach aches and nausea, etc. began. He was even admitted to our local Children's hospital in November for a severe upper respiratory infection that affected his asthma and blood oxygen levels and for the first time ever, did not respond to therapy. He was on oxygen for 3 days. Not realizing all this was likely due to Singulair, I took him to his ped. pulmonologist, pediatrician, ped. allergist, a ped. gasteroenterologist, and an ENT. None of our doctors suspected the Singulair--and I still have confidence that they are all good doctors. In December, he had surgery to cauterize the inferior turbinates in his nose and remove his adenoids to try to alleviate the sinus infections. At the same time, we had an upper G.I. series done to see if we could find what was causing all the stomach aches and reflux. The GI doctor found nothing. I am just sick to think that Singulair did all this to him, that we put him through surgery to try and "fix" the symptoms, and doctors and parents didn't know enough about the side effects of this drug to suspect it as a possible culprit!! I called our pulmonologist and pediatrician this morning to report my suspicions and took him off it. I sure hope his symptoms will improve.