In the last few weeks our cat, who used to happily use the litter tray, has started pooing outside the litter tray. Today, there was free litter but he still had two poos outside the litter tray - but had a wee in the litter tray. We also have a cat flap, so he really has no excuse for pooing in the house. We have a 3 year old DD so I really need to get this resolved - any suggestions?