Connection issues

I don't know whats going on, I just got demoted because of random lag. I do a ping test and I get 89ms. I go into a league game I get around 300. The strange thing is this doesn't always happen, sometimes my ping in league is 140ish, then in some random games it goes up to 300. I try to reconnect it goes away some times other times it stays. I cannot play ranked anymore because of this random lag.