I would suggest that you change your email account password. It sounds to me like your account may have been hacked. Try changing the password, oh and don't forget to make the change in Outlook as well, and let us know if that helps.
If you want to run a scan you could try ESET:
DownloadESET online scanner
Click on START, it should download the virus definitions
When scan completes, click on LIST of found threats
Export the list to desktop, copy the contents of the text file in your reply
You may not get a listing if nothing is found