Thanks for your response @rchoi, it was simple in the end I just didn’t know where to edit the robots.txt file.
@wengerball. Remove your whitelist settings, this will just cause 403’s when twitter tries to read image. Go to your pull zone and manage. There is an SEO tab where you can turn robots.txt on and enter custom values. Just enter these and all should be working again.
User-agent: Twitterbot
Disallow: