For your actual email account or it just looks like it's coming from your email address?
If it's from your actual account then change your password and maybe your security questions too. But they don't need to use your actual account to make a email appear as an email you sent. They simply spoof the sender email address (and possibly the name too) and send the email from any email service they happen to use. In that case there isn't anything you can do about that. Once your email address is "out in the wild" anyone can use it for spoofing. And it may not be you that was hacked to get that info. It might be any one of your contacts with you in their email contacts list.
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