We stopped off at the vet on the way home from the Cape. Really glad I did. It wasn't a stone that had blocked her, it was sludge, and it was in the process of blocking her again. Bloodwork from the other day indicated a problem with her kidneys. Really high phosphorous - three times normal. And high calcium, thus the sludge. She's on Aluminum Hydroxide to try to lower the phosphorous. At least the vet cleared what was in her. I'm hoping the meds can take effect before she gets blocked with sludge again.