Hello,
Here are some things that you can try:
DISK UTILITY STEPS:
Go to the Disk Utility and verify your disk permissions and disk. If the Disk Utility finds any problem with your disk permissions, then click "Repair Disk Permissions". If there is something wrong with your disk, shut down your computer, and turn on your computer using Recovery HD. To do that, while your computer starts up, hold Command+D keys on your keyboard. The Disk Utility will show up and there repair your disk (once again, if there's something wrong with the disk itself.)
DELETE CC (CUSTOM CONTENT):
Delete all the custom content you downloaded from the Store and from external sources.
DELETE MODS:
Do you have any mods or custom content installed? If yes, some may be out-of-date and may be conflicting with the game. Try deleting the mods or moving them out of your Mods folder to your desktop temporarily and then run the game. If your game runs properly, then there is definitely something wrong with the mods.
I hope any of the steps will get your problem solved. Please keep me posted.
Good luck.
