Fatal error: Allowed memory size of 67108864 bytes exhausted

Also talk to your host or clean out error log files and cache files that you have access to via cPanel or FTP.

@esmi’s suggestion will help too.

Also, check the P3 Plugin Peformance Profiler. http://wordpress.org/plugins/p3-profiler/

Just because your error is showing a WP core file, doesn’t mean that it was the one that used up all your memory. The profiler will help youlearn which plugins are fat and you can then make a decision if they are all important to your or not. Removing fat plugins may reduce the memory load of your site.