The last week or so, Rufus has started doing his poops immediately outside his tray as opposed to in it. He is still happy to wee in the tray, but consistently poops outside it. I've tried cleaning it out more regularly (three times a day) and changing the litter - but he still does it. The tray he has is a corner tray with a hood. Any ideas? The smell is driving us mad! Plus if we don't get to it before the dog, he eats it!