Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
Behavioral changes in children with epilepsy can have a variety of causes. Postictal (following seizure) changes can just be part of the effects of the seizure, but these typically last a few hours or at most days. Children with epilepsy can have behavioral changes as a result of their reaction to the diagnosis if they understand it. In addition, patients with epilepsy are at higher risk of developing depression, and in children, this depression may be expressed as behavioral changes and agitation rather than the more typical symptoms of depression.
Most often, behavioral changes in children with epilepsy are the result of their seizure medications. Some seizure medications, such as leveteracetam (keppra) but also others can lead to a variety of behavioral problems such as irritability, aggression, and impulsivity. Sometimes, an alternative seizure medication is necessary when the behavioral changes start to interfere with function.
Discussion of your concerns with your child's neurologist is recommended. He may benefit specifically from evaluation by a pediatric epileptologist, which can be found in most tertiary care centers (such as university hospitals etc).
Please note that keppra or any other seizure medication should not be abruptly stopped but rather that this should only be done under supervision of a physician, only after specific instructions have been given, and usually only after another seizure medication has been added and the appropriate dose reached.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.