I understand, but on the internet you have to watch out and be aware of these sorts of things, since there are lots of idiots and jerks out there, bored and wanting to try and make others as miserable as they are
But if it's fanart, then there isnt too much to worry about it truly being stolen (unless it has no signature and watermark). And your style is very easily to notice too from the fandom, especially since not many draw cragmites
but if you can track down those people and the pictures, you can try asking them first to take them down. And if they dont, then that's when you have to try reporting.