It sounds like renal problems to me. Renal issues can accelerate suddenly and become fatal so quick diagnosis is essential.

The sterile "litter" which is used to collect urine samples used can be transparent, looking like small quartz stones (what my Vet uses here in Montreal, Canada).

See a veterinarian who specializes in domestic felines or one in general practice who loves and has cat(s) as companion pets.

Renal problems can come on at any time in a cat's life (just like with humans, me being one with renal problems). For Feline Renal issues, click onto http://www.cat-health-behavior.com/k...e-in-cats.html

It also can be a thyroid condition which can be controlled medically. http://catthyroid.com/

Your Del may need a new diet, daily meds and careful care -- please post back to let all of us know how Del is doing. Evey pet lover worries about all pets...