Alien sim glitching my game

[eriinm]

Hi, I’ve been playing Sims 3 for years now (although I have never played with an alien until this game) and have never encountered anything like this before.
One of my games, that I played for hours the other night with no problems, randomly started glitching an hour or so after I started playing yesterday morning, after my newish alien sim aged up to a child.
Just for some more detail; I have the Seasons, Pets, Outdoor Living and Supernatural expansion packs installed but those are the only modifications that have been made to the game, and I just updated Origin before I played the other night. Also, when I age up the alien sim, unfinished homework appears in her inventory immediately as if she just got home from school even though she had never been before as it was her first day as a child - this was my first clue that she was glitchy.
My sims (all the sims in the family) kept randomly becoming invisible and appearing again, the bubbles to select actions wouldn't go away after I clicked one, I couldn’t cancel actions, they couldn’t complete actions and often attempted to but then teleported back into a standing position with a blank queue, I couldn't move them into a new house as it never processed the move after I finally managed to get them onto a computer after multiple attempts, entering build/buy mode or edit town mode did nothing except make the menu at the bottom disappear while my sims continued trying to do things by themselves (sometimes they’re successful, sometimes not, but time keeps moving and I can’t control them), and I couldn’t select anything while in this mode even though my mouse made the clicking sounds (so the game became even more useless in build/buy or edit town mode), etc.
When this began to happen, one of my sims (the newly aged alien child) was about to start getting ready for her first morning of school as normal and the whole game glitched. The sleeping parents teleported into a standing position into the middle of the bed and her older twin brothers were as useless as she was. I couldn’t play the game at all, and this issue wasn’t present on another game I played after this happened, or my other previously created games - it seems to just be this one, with the alien.
I tried updating the game, restarting my laptop, saving the game and quitting, quitting without saving, resetting all the Sims, going into build/buy mode, trying to get them to move house, and nothing has worked - I managed to make my game playable again by rolling the game back to the auto backup from before the glitching occurred, however minor glitches (similar to the ones I listed but fixable kept happening, as well as many others that I can list if necessary.

I then tried aging up the alien to a teenager and an adult to see if the glitching was associated with the child stage, but the glitches just continued until I moved her out of the house.
I’d really like to keep playing the alien sim one day, so how can I fix her? Will this happen with every alien sim I play?
Thanks