An 8-year-old boy received a hit to the head with a ball during a physical training lesson. Over the next few days he was complaining of headache and nausea and had three episodes of vomiting. His parents did not take him to a physician. Six months later, the parents and the teachers began to notice that the boy started experiencing episodes, when his face would become red and he would freeze for a few seconds, focusing his gaze on a single point. While in this state, the boy was not responding to people calling his name. What is the most likely diagnosis in this case?