Hope this info helps. My son also has experienced febrile seizure from that age of 4 months until he was 2.5 it is a scacry event, but common in young children that are prone to high fevers.
A febrile seizure is a convulsion in young children caused by a sudden spike in body temperature, often from an infection. Watching your child experience a febrile seizure can be alarming. The seizure may only last a few minutes, though it may seem like an eternity.
Fortunately, febrile seizures aren't as dangerous as they may look. A seizure triggered by a sudden fever is usually harmless and typically doesn't indicate a long-term or ongoing problem. Often, a febrile seizure occurs before parents even realize that their child is ill.
Febrile seizures affect 2 percent to 4 percent of children between the ages of 6 months and 5 years. Although fairly common, a febrile seizure is still reason to seek medical attention, especially to check for any serious cause for the fever.
If your child is prone to febrile seizures, you might be able to prevent them by treating a fever early. However, most febrile seizures develop suddenly and without warning. Being sure the child is safe during a seizure, offering comfort afterwards and following up with a doctor's visit are good approaches for handling a febrile seizure.
good luck, and hang in there I know this can be very scary.