What was the term for these weird visual symptoms?

When I was 12, I had a really high fever and I was seeing a purple diamond pattern over my entire field of vision. When I was 14, it happened briefly in PE. It completely obscured my vision for a fraction of a second before fading from the center. It was accompanied by seeing trails behind some moving objects. What's this called, and what could have been causing it when I was 14? I was pretty sleep-deprived at the time, but I was still getting 2-3 hours a night, so my friend didn't think that was the cause.