one of my persians tends to do this when anything different happens in house when i spoke to vets they advised me to wash the area he used with biological wash powder then surgical spirit then put a litter tray there.I also bought a plug in airfreshner from vets and he has stopped doing it in house now. They said it was anxiety with him and stress due to something different happening in house. He has done it in bath and on bath mats before now . Still has the odd accident in conservatory but not as bad since we had a cat flap fitted. Would ring your vets and ask them about about the airfreshner the 1 i have is called feliway and cost around £25 then you can just buy a refill for it then not sure how much they are as this is first one i have had .