My 9 year old son was on Singulair for about 4 weeks. His whole ...

My 9 year old son was on Singulair for about 4 weeks. His whole personality changed. He cried all the time, he would not sleep alone, he had headaches, dizziness, tummy aches and horrible nightmares. His whole bodyy broke out in a rash and even now after 2 months of taking him off he is still covered in a rash. He was so sad all the time and so irritated. He would yell at us and was so angry all the time. He still is not back to himself. I see where people say their kids are back to their old selfs. I know my son is better but he still is having a hard time focusing in school and crys easily. He seems as though he is not the same child. I wonder if these side effects can cause permanent damage in some way. This is all so scarey. Drs. need to talk and help these children, NOW