At first I thought, maybe, it was a coincidence. But seeing your follow-up posts about the guy's reactions, my gut tells me that, yes, he is ripping you off and knows it.
I don't know where you are, but here in the US, in some cities, there is a group called 'Volunteer Lawyers for the Arts', who might be able to help. If you cannot contact the offender through the site, then you should contact the site itself & the server, and getting a letter from a legal firm will make them sit up and take notice more than getting a letter from you.
That's the thing about people who rip off others people-- they always think that, either they are going to get away with it, or that the other person is simply going to be powerless to do anything meaningful back at them.
And-- if you haven't yet registered the copyright, do it immediately. Even though you probably cannot copyright the matchbox camera itself, you can register your article. And see if you can get documentation of when you originally posted your article.