Some what frequent game freezes

I hadn't played the game in like 2 weeks, and i had forgotten why i stopped playing, so i decided to boot up the game and have a go at the game again, to my surprise i was having fun, all was well and good, next day i decided to play again, this time with a friend of mine, 3 games in and it was going well, i was my last game out of bronze (Yeah i know "XD BRONZE KIDDDD") but suddenly my game started spontaneously freezing, like my frames went from 60fps to 15fps, we lost the game and i lost my promos. Next day i didn't really feel like playing league, i was still a bit salty. Now today, i started playing again, i didn't dare to go on ranked because of what happened last time, but i played to quick play games and all was well, well except i lost both of the game. but into the third game half way into the game my game frooze completely, no warning or anything, my mouse was the only thing moving, i tried to change tab, but it wouldn't work so i decided to press the power button. i then turned it on again and opened up league, and of course as my luck goes the manager crashed, then the crash report thingy came up, and crashed as well. Pretty weird, i then tried again and got into the game, we won anyways, but in total it took me 10 minutes to get back into the game. then i played 2 more games and all was well, but then the 3rd game it happened again, exact same scenario, middle of the game, and playing support, and always 2 games between, i haven't played since last game, but it does seem there is a pattern. Also i do for a matter of fact know that its not my computer that is the issue, i can run Overwatch and many other games on this computer without issues.

If anyone could maybe explain whats happening, or possibly help me, i would greatly appreciate it, or just tell me if you are having a similar issues