My son is 11 yrs old. I can not believe what I am reading. My son...

My son is 11 yrs old. I can not believe what I am reading. My son has been taking Singular for about 3 yrs for asthma and allergies. My son was always happy and the most confident child I know, he did great in school. All of a sudden about 2 years ago everything has changed. He is always moody, upset, has fits and argues about everything no matter where. My husband and I could not understand it, he was never like this. His grades have gone down dramatically. One teacher told us she taught he had hearing problems and that I should have him tested. We did last year and they said he had no problem and that he needed his adenoids taken out that were swollen and compressing his ear drums so we had them taken out. I do not see a difference we still believe he has problems hearing at times we have even kind of test him at home at times and he can not hear well, he has even been talking very loud as if he had a hearing problem. His academics still continue to drop. We taught this is just a phase he is going through. Recently at school the teacher told me he might have ADHD and that maybe I should put him on Medication. I refused !! You see I have a 16 yr old that has ADHD and had all the symptoms from an early age. But my other son never showed the signs he was alway attentive and did well in school. He has been complaining of headaches and stomach aches we had him checked out and nothing we taught maybe he does not want to go to school or wants attention. He is also depressed at times. My question is will this go away when he stops taking this medicine. I have not given it to him since 3/21/08 that my sister in law told me about the news. I have an appointment with his doctor next week. I feel so horrible for not even considering that this medication might be the problem.