After reading this week's NYT article on constructing, I was inspired to try.  I'm now completely absorbed in filling a 15x15 themed puzzle, and feel great about a theme inspired by my kids.  But, all that being said, I'm still relatively new to crosswords generally (I got the NYT app only about a year ago and was hooked) so I haven't much of a sense of whether I'm inadvertently repeating something that's been used before. Any advice for a newbie like me on how to check whether or how often your theme has been used before?  
I was also spooked by the postings on the plagiarism scandal, though somewhat reassured that duplication does happen by the articles linked there.
Thanks in advance