Was email send from my own account?

Last night I got an email on my business Gmail supposedly from my business Gmail account. It was the usual extortion stuff saying they had hacked my email and had naked photos of me and they’d send them to everyone unless I pay $850. And my who system had rat ware in it so if I changed my password they would know the new one. I’ve since changed my password.

There are some problems with this like they said my email at the time of hack was 345276 which it has never been (it’s much more secure). Didn’t supply any photos. My web cam has had tape over it since I bought the computer. And they didn’t supply any contacts.

However, when I click show original the only email address I can see in there is mine Sales@domain.co.uk with a lot of random digits compared to when I send an email to myself. I guessing this has something to do with the spoofing of my email? How do I find out where this was really sent from and if it was from my email?

Thanks in advanced