PHP ERROR

I am using the theme polish.when i visit my website it shows this error
“PHP Error Message

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 344381 bytes) in /home/a7434150/public_html/wp-includes/shortcodes.php on line 188″

What should i do.This happens on the home page and some other page as well.
I am using a free hosting site.It worked up until now without any problem.

What should i do.
Here is the link to my site: http://techhype.freeiz.com/
HELP!!!!