Seizure Symptoms????

Hi,

My son is 4 years old, he was diagnosed with epilepsy about a year ago after having about 4 seizures (grand-mal) and an EEG. Since then he was put on Keppra which did very well for him (controlling the seizures, but it did cause behavior issues) up until about a month ago. He started having break through seizures about every week then three times in one day, they increased his dosage already three times and he is currently at his max dose. He is in two days without a seizure. My main concern though is this new behavior I am witnessing. My son is starting to stutter, which he never has before, and he is doing small head jerking movements while he stutters. It seems almost as if he is getting stuck in the middle of a sentence or action. For example, he will try to tell me a story of him getting in a car and he will say "and then I got in the cuhh-cuhh-cuhh-CAR" while he is stuttering his head is jerking and he is trying so hard to get the word out and when he finally does he kind of shouts it. This behavior is getting increasingly worse as the days go by.. he is doing it now at least once every few hours. I have told his pediatrician and his neurologist of this new behavior and literally the only answer I got was "it may be related to the epilepsy" but they are waiting for his MRI which is scheduled next week to see if anything has changed since his last one. I wish they would have given me at least some explanation as to what it might be or if this behavior itself is actually a type of seizure. Please, if any one has any information that can help me please share. I am so worried!