Welcome to the Pet Rescue Community
Do you need help with your game? Ask the Community for help.
Have you tried these steps already: https://goo.gl/owWByB Including clearing the cache and changing browser types?
If the issue persists still, please try reinstalling the game app from Facebook. Don't worry, it won't affect your game progress:
Go to “Settings => Apps” and press the “x” next to the app in question.
Clear cache: http://www.wikihow.com/Clear-Your-Browser's-Cache.
Then restart your PC and add the game to your Facebook account again.
I hope this helps!
Jenny