He may have stolen your artwork, renamed it (really badly, I might add), and attempted to sell it as his own for hundreds of dollars.
Exhibit B (screenshots from the now defunct website)
Luckily, I have yet to find any of my work in here, but there are over 500 pages of screenshots to look through. I'm thinking I'll mostly be safe since I deleted my deviantART account a while ago. But there you have it...I suggest you look through it yourselves just in case.