Abnormal EEF

At the age of 15 months, my son had 3 seizures in the span of 7 hours after 3 days of no food or liquids due to gastrointeritis. He was hot to the touch before each seizure but no official fever was recorded. He was hospitilaized and put on a drip to get some fluids back in him and we were told that he had febrile seizures. He had an EEG recently (age 19 months) and the results came back abnormal stating that he had low activity in the left part of the brain. They ruled out that he had febrile seizures and believe it to have come from this part of the brain. As he's had no seizures since the last 3 (which the neurologist counts as 1 seizure giving they occured in one day), they can't be certain that it's epilepsy or anything else. He has an MRI in a months time, what could it mean to have low activity in the left part of the brain?