Weird event when younger, want explaining.

[Kabuk]

When I was younger my brother had gotten me into video games, I didn't have any money at the time so I was playing flash games (games on a website that are not too complex, usually 2D) and there was one that I really enjoyed playing, but after about thirty minutes of playing my vision went out of focus and it felt like my brain was jumping around in my skull. This really spooked me and I stopped playing that game for a while, but later went back to it and had the same experience that same year. I always thought it was a seizure but looking at the effects of one, it doesn't seem to be what happened, I tried googling an answer and found nothing that related to my experience. I am 17 now and have been playing video games since my experience (I was around 5) and have had no other problems like this. I am very curious as to what this could have been.