Hyperlinks inserted into blank (primarily) content areas

Our website, http://www.rpm3solutions.com, has been hacked…..someone inserted a bunch of links to random sites that are active in all pages except home page. Links are seen on mouse-over in blank areas of the screen mostly, but sometimes on a link we had previously established. Site runs on WordPress 4.0.1 and Centos 5.5-XS. Inserted hyperlinks are not obvious when viewing WordPress HTML code. Did run a trial version of “Siteguard”, which determined that 2 suspicious files were found….one was Google Analytics (makes me suspicious of Siteguard’s value) and a file in a plugin we used.
The Siteguard “suspicious files” findings were:
/wp-content/plugins/si-contact-form/includes/class-fscf-process.php

/wp-content/plugins/google-analytics-for-wordpress/admin/class-admin-menu.php

Have since deleted the plugin (“fast secure contact form”) and rebooted server, but problem still remains.