Clarinex side effects

I have a 3 year old son that was diagnosed back in December with allergies and was prescribed Zyrtec and Singulair, after taking them for a while we noticed that he became very belligerent so we called the Allergist and they took him off the Singulair and put him on Clarinex. We weren't real good at giving him the medications very regularly, but recently I've gotten better and he's becoming very belligerent again. I was wondering if anyone has had any problems with moodiness with either Clarinex or Zyrtec, I know the problems with Singulair and am very thankful that he is off that med, but now I'm concerned about the others...