[GAMEPLAY] Double Left-Clicking to do anything, but Right-Clicking is fine.

So I just had a game today. Right when the game started, I tried clicking on the shop. Didn't work. Unplugged my mouse and put it back in. No effect. Tried a different mouse. No. Only when I was clicking with my second mouse rapidly in frustration did I manage to bring the shop up. Had to double click to pick abilities on level up. Camera controls were just as bad. Could no longer pan across the screen to move the camera. Even tried the key to lock the camera onto my champion. That didn't work. So I spent the entire game double-clicking the mini map to move the camera around. And this is all the LEFT click. Keyboard prompts and the RIGHT click for abilities/spells and movement worked just fine. I did not have this problem when I played yesterday. Tried poking around to see who else had this problem, but anyone who had it was months ago and edited their post that the problem was gone (but unfortunately no explanation how they got it gone). Any ideas?