Denver colorado symptoms and conditions

My 12 year old son was diagnosed with severe infantile asthma at 4 months of age - it was so bad that we had to fly him from Illinois to the National Jewish Center in Denver, Colorado, for a correct diagnosis (I would highly recommend this center for anyone with asthma that is not controlled). He did well until about six months ago, when his asthma became uncontrolled. Our doctor put him on Singulair. My son has been having trouble at school, is at risk of being held back, and his shown behavior problems that he never had in the past. I never put it together - until I saw the news last week. He's now off Singulair and we've seen some improvement, and we're praying for more. Thank God we found out before it was too late...