Spam from myself without it being in my sent messages folder?

You've been "spoofed" and there's really nothing you can do to stop it.

Spoofing is the "forgery" of an address, to hide the identity of the sender, and is usually done by an Automatic Spamming system, that "blindly and randomly", runs through addresses in a sequence, (until they finally hit on a valid address).

It's not actually coming from or thru your account. (see in your sent folder)

One type that's called "Self Spamming"--(go figure)--appears to be coming "from" and going "to" the same address.

Anti-spam experts say----There's nothing you can do, except delete them.

They are a nuisance, but harmless (as long as you don't click on a link in them)----and "usually" don't last long.

If you spam them--you'd only be spamming your own address.

Changing your password won't stop spoofing---they aren't using your account---but are just forging the address.

Well, you know how you get emails from Bill Gates? It's not really Bill Gates who's sending those emails. So when you're getting emails from yourself it's not really you who sent the email either. Someone spoofed your email address and is sending spam. The thing you might like to know is that they can just as easily send those emails to anyone else too. How do you feel about that? Not good. But, there's nothing you or anyone else can do. Click on the Spam button whenever you get one so the email provider will track it and stop the sender.

sounds like a virus.update your virus scanner and get http://malwarebytes.com/

you might want to turn off system restore while scanning because everytime you boot up the system restore would load the virus back up again.turn system restore back on when free of viruses.