I can't play the game anymore, help!

My problem is that in about half my games since patch 9.15-16 the game just freezes and crashes my whole Pc right after. I've tryed using the Hextech repair tool, initiating a full repair, reinstalling the game, playing in windowed mode and have also spent about 2 hours in practice tool trying to figure out what triggers the crashes and have concluded that they are completely random and happen anywhere from the loadingscreen being at 100% to the nexus being destroyed. I usually run the game at 60 fps without trouble but after one of these crashes it goes down to about 39-22 fps until I restart my laptop which I have installed every update that was availale on. I really don't know what to do anymore so I figured that somebody here might be able to help me out. I feel like I could be way higher elo without this problem than I am rn as I am able to still do quite well anyways. Pls help me climb again, this bug or whatever it is makes it nearly impossible to gain lp...