Pytheas theme hacked! Need help

I need help. Not a hard core programmer so am really struggling trying to figure out how to fix someone hacking in to our site (www.stmichaelcyo.com) and putting a link to cialis, viagra, etc in the top right corner (right above the email link). I’m using the pytheas theme from WPExplorer.

It seems that the link only appears when using internet explorer

I contacted my web host (ipage) and they ran a scan but they didn’t provide a solution to fix how to remove this other than suggesting I replace a bunch of files.

Can anyone help me or point me where to look?