My son has been on Singulair for over a year now, and I'm beginni...

My son has been on Singulair for over a year now, and I'm beginning to wonder if the medicine is what his problem is. He's in the third grade, and is struggling really bad in Math. He also has little tantrum fits, and doesn't seem to listen as I think he should. I'm having him tested for a learning disability, but I just wonder if it's the medicine? He was put on it for the Chroop, he seems to get it really easy, and I'm afraid to take him off for fear he might get the Chroop again. I don't really know what to do. Concerned Mom`