Just because the antibiotics are finished does not mean the infection is gone. Is Luna due for a follow-up urinalysis? I was just today reading in cat fancy magazine how some infections take 4 to 6 WEEKS of treatment to prevent reoccurance.

And can you refresh my memory about how many litter boxes you are using right now? 3 of them would be ideal in your situaton, and preferably NOT all in the same location. Maybe Luna just wants another choice in "pottys".