Kirsten,
No sense in beating yourself up over this. You can't help your back problems, and Luna can't help her bladder problems. I am not trying to make light of the situation, but, sometimes, all you can do is just sit back and let things unfold. Hopefully Luna's bladder problems will resolve with another/different set of antibs. Your back WILL resolve itself, at some point, in some fashion. Stress will only make things worse for the three of you. I imagine your doctor knows you are a trustworthy soul, or she wouldn't have extended the offer for credit. Now, take some of that cranberry juice, and add a little vodka, and relax.
Hugs,
Johanna