Unless you have your gmail set up to download to your machine via a pop3 mail client such as Outlook, then it's unlikely your computer is the source of the problem.

Just to make absolutely sure, download, update and run the *free* versions of these two malware detectors: Malwarebytes Anti-Malware and Superantispyware. They are both very good and tend to spot things other detectors don't.

They may well pick up things that have nothing to do with this particular worm too!