Game glitching

Hey, So about a week ago, my game has started glitching. Constant random FPS changes from playing one game normally. The next unplayable. I have a high end gaming pc so thats not the problem. During the FPS drops, my keys would change. Enter would changed from windowed to full screen, V would be my Q ability etc. Its just going crazy. I've reinstalled the game, Repaired the files, Changed the graphics mode, Set the game to high priority etc. But it keeps happening. Its crazy. Need some help pls