An hour following the vaccination, my son threw the most severe temper tantrum of his life. It appeared out of nowhere, and he was banging his head on the ground repeatedly. I was unable to control him. He had never had a tantrum like this. For the remainder of the day on Friday, as well as Sat., he was unusually tired. On Sunday morning I could tell he was warm and gave him Tylenol. I returned from work at 1500, and my husband told me he was disturbed by my son's behavior. He reported that my son was not responding to him, giving him blank stares, and wanting to sleep constantly. I noticed these symptoms as well. On Monday 7/23/2012 my son slept until 11:00 AM and when I woke him, began crying because he was too tired to get out of bed. I also noted that he was twitching in his sleep very frequently. He refused to do anything but sleep all day. The blank stares and periods of refusing to answer when spoken to continued. I contacted the Nurse line at his primary MD's office and was told this was nothing to worry about. This behavior continued and by Wednesday 7/25, everyone who came in contact with my son was alarmed in the change in his behavior. He did not want to do anything but sleep, was having frequent episodes of blank staring followed by extreme somnolence, and frequently seemed to be in his own world, uninterested in his surroundings. Since Sunday 7/22 he began progressively demonstrating perseverating speech and incessant question asking, which he had NEVER done before. He began drooling excessively and walking on his toes. As a Registered Nurse, I found this behavior extremely disturbing and documented it with video and audio, which I will gladly provide. On Wed. 7/25 he appeared to have improved overnight- his energy had returned and he was talking more. In the afternoon, he gave a blank stare for aprox 10 seconds, wouldn't respond, and then said he had a stomach ache and vomited a large amount of saliva. I contacted the nurse line again on Wednesday evening regarding these behaviors, in addition to the frequent twitching, and was told unless he was actively seizing that it was not a concern. On Friday 7/27 I took him back to the clinic. The first physician tried to say it was likely a virus, pointing out a small canker sore on my son's lip. When I showed him a video I had taken of my son during one of his blank staring and unresponsive episodes, he brought in a second Physician who listened to what we said and said that given my son's previous vaccination reaction and history of post-viral cerebellar ataxia following a vaccination, it could be related to the vaccine. He stated he would obtain my son's old records and follow up with us. He called to follow up with us on Sat., at which time we told him that the drooling was still there, and that his energy was fine, except following the blank stares. After these, he would become lethargic and want to sleep. Sunday 7/29 my son appeared to be normal, other than drooling and walking on his toes. On Monday 7/30 at aprox 1200 PM I received a call at work from my mother, who was watching my son. She stated that my son had been fine all day, but when she on a swing at the park he closed his eyes, dropped his head, and wouldn't respond for aprox. 15 seconds. When he did finally respond, he stated he was "so tired" and that his tummy hurt. She had to carry him home, where he threw up four times. It was at this time I realized that he was likely having absence seizures. I am a Registered Nurse, and I feel silly not recognizing this immediately. I have seen these occur before, but for some reason I did not immediately recognize these in my son. We took him to the Emergency room, where he was admitted. An eeg was performed overnight from 7/30-7/31, and this did not show any evidence of seizures, but my son did not have any of the staring episodes during this time. The neurologist recommended an MRI and Spinal Tap be performed. This could not be done until 8/1 due to scheduling, so he remained in the hospital until then. On the morning of the procedure we spoke with the neurologist and decided that because my son seemed so much better that we were going to wait and see if the symptoms returned before having these tests done. We are following up with the neurologist this week.