Could it somehow be a corrupt Origin file? Maybe try clearing the cache or reinstalling Origin.
I know that Sims 4 game saves can get corrupted, so it's wise to use the 'save as' feature sometimes and continue from that save. Whenever I notice my game getting a little weird or stuttery, I use 'save as' to refresh it. Sometimes it helps, sometimes it doesn't.
Also, have you tried bumping back to a previous save in your original game? There is a way to roll back the save to the one you used before the most recent, in case something corrupted in that gameplay session. Use the icon in the lower right of the picture of your save.
Also, restart your computer if you tend to keep it running and it hasn't been turned off in a while. Sometimes the need for updates can do weird things.
Good luck, I hope you find the issue.
