Why is my internet suddenly very slow?

Well, one day I'm playing League of Legends with my brother perfectly fine, and the next day, my ping is suddenly spiking every second, being about 12 for a few seconds then suddenly 300.

At first I thought it was just League of Legends but in fact it is my computer having this problem. I can't load videos in under 5 minutes, and web pages take long to load, and even this page as I tried to ask a question. I tried everything, I tried disconnecting and reconnecting to my internet, and disable and re-enabling my network adapter. I tried closing all my background programs (also those that did not use the internet), I tried running a virus scan with AVG, cleaning my registry, and just anything in desperation. I also tried bringing my laptop to different positions of my house.

The catch is that it is happening to only me. Both my brothers, who both are playing League of Legends, are having their perfect internet, and have never been affected by this. It's the same for my iPhone. For some reason, this is only happening to my computer, and for two days now.

Someone please help me!

Added (1). I also reset my router, which did not affect my brothers' perfect internet nor my horrible internet.

I don't know but if you go on the forums a lot of people are having this problem (me also).
I've had this problem for about a month, my ping is normally 500 but rises up to 900 and has big lag spikes.
I heard Riot is trying to fix this.

I'm not having the iPhone problem. Its only with League for me and a lot others.