She didn't eat much (even though I offered baby food chicken) and is just kinda loafing around (although she was a little more mobile than before). She didn't even protest too much when I pilled her. So I will be calling the vet back.

Bloodwork/urine is normal, so it's not kidney; next step is a sonogram to examine for tumors/blockages.

ETA: I appreciate the kind words and thoughts. It's helping me to not do a major freak-out right about NOW.