Oh Jen, my heart goes out to you for having to go through this.
But I think your solution by separating them is a good one.

I remember when my RB C-Fer had UTI, he would also go in the bathtub or the sink and also on the kitchen floor which was white tile at the time. I didn't know anything was wrong with him until he started doing this and I noticed blood in his urine. It was almost like he was telling me, "Look Ma, there is something wrong with me." If he did it anywhere else in the house, I wouldn't have noticed.

You didn't mention if there was any blood in the urine. Was there? Cause this is a classic sign.

My prayers and thoughts are with you Jen. I hope you find out who it is and that it isn't anything serious.

BTW, you're Holy pee-spots batman comment is hilarious.
You need a sense of humour in times like this.