Explaining my epilepsy to my 4 year old son


I am trying to find a way to explain to my 4 year old son that I have epilepsy. He has never witnessed me have a seizure in the past. I was given a DVD by Epilepsy Toronto that tries to explain a seizure through the use of animated stick figures. However, the content as a whole seems to be too advanced.

I was hoping that someone could provide me, or point me in the direction of any websites, dvds, books or other materials that I could use to help explain at a 4 or 5 year old level

Any assistance is greatly appreciated!