I think it's going to be hard to prove it's actually your picture without some kind of obvious watermark or something. 15 people could have linked that picture, how can they determine whose it actually is? I know you said the deal about changing the link, but all that proves is that you have heightened access to the site the photo Cookie linked from.
I'm not trying to disprove that it's your picture or anything, all I'm saying is I don't think you have much to stand on.