Thanks page and email not working

This plugin is great and has worked for 2 years with no issues. Lately, and I am not sure when, the thanks page and email reply stopped working. It is for a festival and does not get used until this time of year through September.
Checked the email flow chart, everything is set as it should be. The thanks page comes up blank or goes to an error. Changed settings to same page – same thing, changed to a new page no difference.
Database is updated with entry, but no email and no thanks page.

I do get this error:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.

Php error log

20160630T152757: http://www.esquimaltribfest.com/index.php
PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 65552 bytes) in /hermes/bosnaweb21a/b412/ipg.esquimaltribfest/wp/wp/wp-includes/shortcodes.php on line 351

20160630T153134: http://www.esquimaltribfest.com/index.php
PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 130968 bytes) in /hermes/bosnaweb21a/b412/ipg.esquimaltribfest/wp/wp/wp-includes/wp-db.php on line 2319
PHP Fatal error: Call to a member function get() on a non-object in /hermes/bosnaweb21a/b412/ipg.esquimaltribfest/wp/wp/wp-includes/cache.php on line 123

20160630T162443: http://www.esquimaltribfest.com/index.php
PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 65552 bytes) in /hermes/bosnaweb21a/b412/ipg.esquimaltribfest/wp/wp/wp-includes/shortcodes.php on line 351

20160630T162506: http://www.esquimaltribfest.com/index.php
PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 65552 bytes) in /hermes/bosnaweb21a/b412/ipg.esquimaltribfest/wp/wp/wp-includes/shortcodes.php on line 351

20160630T162628: http://www.esquimaltribfest.com/index.php
PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 65552 bytes) in /hermes/bosnaweb21a/b412/ipg.esquimaltribfest/wp/wp/wp-includes/shortcodes.php on line 351

20160630T165404: http://www.esquimaltribfest.com/index.php
Participants Database: no valid email address was found for the user receipt email, mail could not be sent.

Thanks Terry

https://wordpress.org/plugins/participants-database/