My Chartreux has decided to start peeing on the carpet by the sliding glass door. He doesn't do it everyday ut we haven't found a method to his madness. He started this before he was fixed and has continued after his surgery. He only pees on that bit of carpet in front of that door. I have put Nature's Miracle on the carpet by the gallon and have had the carpet treated and cleaned professionally. I have even kept the blinds closed on that door but that doesn't seem to help. What should I do next?