I'm calling the pediatrician in the morning!! My soon to be 6 year old son was diagnosed with RSV, and has been taking Singulair for "asthma" since he was 4. He has become more aggressive in the past 6 months, and has been complaining of leg pains for some time now. Headaches and the nausea episodes were too far apart for me to consider them a side affect. He has constant skin rashes, and itches them until they bleed. The ex calls the rash "exema" and treats it with cream. I tried to have the medication changed about 6 months ago, but my exes insurance will not cover a different "tier" of medication and the doctor said it worked best. Boy are they going to get an earful from me. I've also noticed that when I forget to give him the Singulair for a couple of days, the rashes and itching seem to clear up faster. Thanks for all the posts. He will not be taking it while with me anymore.