I feel I have the same problem!!!!! I've changed my password, even how my name appears, but nothing seems to stop this!!!  I am receiving emails in my junk emails from my own email address.   They do NOT appear in my sent folder.  Please do something quick!!  I have no idea how long this has been going on, normally I just empty my junk and don't look at it, but I stumbled onto it when I took a look at  "junk email", sorted it my send here is what I found: