Need help fixing many errors in error log

I’m having trouble with my suddenly very sluggish site. I checked the cpanel error log, and was able to fix one thing by deleting a plugin, but I have no idea how to fix the ones below:

1) [warn] RewriteCond: NoCase option for non-regex pattern ‘-f’ is not supported and will be ignored.

2) [error] [client 170.135.112.14] Failed loading /usr/php/53/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/53/usr/lib64/php/modules/ZendGuardLoader.so: undefined symbol: gc_remove_zval_from_buffer, referer: https://glutenfreerecipebox.com/gluten-free-mashed-potatoes/

3) [error] [client 182.93.55.247] Failed loading /usr/php/53/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/53/usr/lib64/php/modules/ZendGuardLoader.so: undefined symbol: gc_remove_zval_from_buffer, referer: https://glutenfreerecipebox.com/gluten-free-cupcakes/

4) And more like no. 2 and 3 above.

5) [error] [client 64.118.125.249] Failed loading /usr/php/53/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/53/usr/lib64/php/modules/ZendGuardLoader.so: undefined symbol: gc_remove_zval_from_buffer, referer: https://glutenfreerecipebox.com/wp-admin/post.php?post=30008&action=edit
Use of uninitialized value $1 in concatenation (.) or string at /usr/local/cpanel/cgi-sys/fourohfour.cgi line 31.

6) I have had a parse error for months now, but it does not show today, yet. I can’t recall the file now. In the past I replaced the file with a fresh one from WordPress, but it didn’t help. It was the same exact file.

In the Advanced Error Log I found a few errors as well, one being:

1) SHTML Wrapper – 404 Not Found.

I’d love to hire someone who was reasonably priced if no one else can help.

I’m using themes Twenty Ten, Thirty Ten, and I see

Thanks!