My 6 year old son was put on Zyrtec 8 days ago and about 3 days a...

My 6 year old son was put on Zyrtec 8 days ago and about 3 days ago he started showing symptoms of emotional outbursts, (crying, screaming, etc.). He hasn't been listening and has showed outbursts that has caused a great concern in our family. He has not stopped th outbursts and he said that he cannot explain why he is so upset. Something needs to be done to this medicine after reading these side effects with other children. The side effects are the similar in nature to what my son has experienced.