HELP! Unknown Errors, I'm new to WP

When I log into my site it says:
DataTables warning (table id= ‘productTable’):
DataTables warning: JSON data from server could not be parsed. This is caused by a JSON formatting error.

Upon trying to edit almost anything the page goes blank and says:
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 85 bytes) in /home/ugcafe/public_html/wp-includes/plugin.php on line 186

Having issues with CART66 and gravity forms since I tried to download a new form plugin this morning…