RESOLVED: I thought I'd put the solution for this issue here, in case anyone finds this and has the same problem:
1. Uninstall The Sims Medieval
2. Copy all your games to desktop (just in case if Origin * up)
3. Uninstall Origin
4. Reinstall Origin
5. Reinstall The Sims Medieval and when it asks if you wan't to install Pirates and Nobles too, click NO (or uncheck the box)
6. Wait for The Sims Medieval to finish downloading, then go to the "additional contents" tab and install Pirates and Nobles.
7. And that should fix it - did for me anyway, it seems to be some weird glitch with Origin.
Only catch with this is, that it'll delete all your saves and stuff. I hope that's not an issue, but it's the best (and only) solution I can think of right now.
