Fatal error: Allowed memory size exhausted

Hello yesterday I got this message on the home page of my blog. I’ve never seen this before:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 747525 bytes) in /home/chaindlk/public_html/wp/wp-includes/formatting.php on line 948

I proceeded to upgrade to the latest version of WP earlier today and the message disappeared but hours later it reappeared.
Can somebody help me troubleshoot this?

Thanks a lot