I've heard that putting some sort of water mark/logo/some identifiable feature that ties to your name/profile that clearly makes it yours in a corner (or really any location you want) can help with these sort of things going forward. I think watermarks are the most difficult to remove and would clearly show an altered image. Most folks I know that do this generally use the @instagram name/business (simple @boxrocket or whatever you want to use, don't gotta be all about the @). Seems to work in the detailing industry as there are always non-legit guys trying to rob professional photos to make themselves look better.