Someone is hacking my email address?

First run a virus scan. That should always be your first step. Then, before you log back onto your email, go to a different computer on a different network (any local library probably has one, or you can use a friend's machine) and change the pword from there. If possible, wait a few days without logging back on and see if any spam is still being sent. If so, then the problem is almost certainly outside your machine; the company hosting your email may have a breach on their own servers. If not, but the virus scan didn't turn up anything, then you might have some kind of nasty malware hiding on your computer somewhere that the scanner isn't sophisticated enough to detect. Similarly, if the virus scan is interrupted or stopped while it is trying to run, that is another good sign of malware.