Ridiculously high ping in game,League of legends unplayable!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

So, recently my game is fuking itself. i get average over 400 ping,and up to over 5000 ping EVERYGAME.!!!This game is unplayable for me. Does anybody know the reason??? Is it because im using WiFi???(i have 15m speed which is not bad, and i dont have connection issue, and it never happens when i play other online games). So i dont know if the problem is on my end or what. PLZ help me!!!! Thank you!!!!