Singulair and aon

My son is almost 9, he has been on Singulair for 3 years. Last Friday the pulmonologist took him off of it. My son has been sleep walking since about the time he started singulair, have noticed major behavior changes. He gets very angry over nothing, he is extremely sensitive, he is not the happy little boy he once was. He has horrible dreams. Over time this has gotten progressively worse. I have to say that since last Friday when he was taken off the singulair, I have noticed a huge difference. My happy little boy is coming back! I told the Pulmonologist my concerns ans could this be side effects and he replied "YES", Also, he feels that my son has outgrown his asthma which is wonderful. I feel so horrible for all these children and families going through this. Parents, remember you are your child's best advocate. don't let the children suffer.