What Causes Anxiety After Taking Keppra For Seizure Disorder?

I was recently, within the last two weeks diagnosed with seizure disorder. I had an observed seizure at work. My body stiffened, I foamed at the mouth. Back in August, I was home alone and blacked out. I have had an EEG, EKG, MRI, CT Scan and bloodwork. All tests are normal. I saw a neurologist and he put me on Keppra 500mg BID. I have experienced anxiety the past week. I have had sinus area headaches for the past two weeks and the week before the observed seizure. I do not normally have headaches. I am 44 years old and trying to process this new diagnosis. Do you have any insight you could share with me?