HELP! Have I been hacked??

HELP! I’m getting emails from Wordfence that say the following… What do I do and should I be concerned???

1.
This email was sent from your website “Strength In Numbers” by the Wordfence plugin.

Wordfence found the following new issues on “Strength In Numbers”.

Alert generated at Wednesday 21st of December 2016 at 01:44:15 AM

Critical Problems:

* File appears to be malicious: wp-content/wp-zelf.php

2.
This email was sent from your website “Strength In Numbers” by the Wordfence plugin.

Wordfence found the following new issues on “Strength In Numbers”.

Alert generated at Thursday 22nd of December 2016 at 01:27:18 AM

Critical Problems:

* WordPress core file modified: wp-includes/theme.php

* File appears to be malicious: wp-admin/includes/page.php

* File appears to be malicious: wp-admin/js/template.php

* File appears to be malicious: wp-content/plugins/gravityforms/print-entry.php

* File appears to be malicious: wp-content/plugins/jetpack/class.jetpack.php

* File appears to be malicious: wp-content/plugins/wordfence/lib/menu_sitePerf.php

* File appears to be malicious: wp-content/uploads/2014/global.php

* File appears to be malicious: wp-content/uploads/delightful-downloads/2015/05/index.php

* File appears to be malicious: wp-includes/SimplePie/Content/sql.php

* File appears to be malicious: wp-includes/SimplePie/XML/diff47.php

* File appears to be malicious: wp-includes/images/wlw/template98.php

* File appears to be malicious: wp-includes/random_compat/test.php

* File appears to be malicious: wp-includes/theme.php

Warnings:

* Unknown file in WordPress core: wp-admin/includes/page.php

* Unknown file in WordPress core: wp-admin/js/template.php

* Unknown file in WordPress core: wp-includes/SimplePie/Content/sql.php

* Unknown file in WordPress core: wp-includes/SimplePie/XML/diff47.php

* Unknown file in WordPress core: wp-includes/images/wlw/template98.php

* Unknown file in WordPress core: wp-includes/random_compat/test.php