"This code has already been used" on existing gameplay

I brought the Sims 4 a while ago and played with relatively little problems popping up.

I then had to install the latest origin update and my game is gone! I am now told I have to "activate" the game (which I thought was just maybe part of the update) and when I put in my code I get "This code has already been used".

I cant get past that point!

I have tried looking around origin itself and "reload my games" and all that stuff. It's my only origin account (it's the only game I use on it), and I have reset my laptop, etc, and I am still stuck.

I can't find a way of EA accepting it's an existing code because it's the one I was using before this update and it's really stressing me out.