I just got permbanned??

I've been playing league for about 3 years now, and today i just randomly got permbanned for "using third party software. I've never touched that sort of stuff as it is cheating, either way i don't even know how to. I need help please, i love playing league and ive randomly been banned. My last game that i played was as rammus in jungle with my 2 best friends, im not sure if someone hacked my account but ive never used hacks before ever. Please help..

Edit: THERE ARE 2 MORE GAMES ON MY MATCH HISTORY, ONE AS THRESH AND ONE AS YASUO. I AM A THRESH MAIN BUT MY LAST GAME WAS AS RAMMUS WITH MY 2 FRIENDS HgBear AND Meowlicious!!!! FLASH IS ON D IN THESE GAMES, I NEVER BUILD ADAPTIVE HELMET ON THRESH, I NEVER GET MORE THEN 5 KILLS ON THRESH (UNLESS IM DOING OFF META BUILDS), I NEVER BUY CONTROL WARDS BECAUSE I JUST FORGET ABOUT THEM LMAO, I BARELY PLAY YASUO AND WHEN I DO I NEVER GET THAT MANY KILLS OR BUILD STERAKS GAGE, AND IF YOU PAY ATTENTION IN THE YASUO GAME THERE IS ANOTHER YASUO ON THE ENEMY TEAM, MEANING IT WAS BLIND PICK. I NEVER PLAY BLIND UNLESS DRAFT ISN'T WORKING OR IM PLAYING WITH AN UNDERLEVELLED FRIEND. I ALSO NEVER PLAY WITHOUT MY DUO PARTNER Meowlicious.