I haven't added a litter box. I just bought a bigger one. I've been using the same litter (crystals) for a year now and sometimes change up their food. Litter box is in the same place. I have made an appt with the vet. The only thing I know to do is keep the bedroom door closed. That is the only place she does it at. So, what will I do if there is nothing medically wrong with her? I am just blown away by this. It is so nasty...