I had an elderly puss who did the same thing, and she wasnt sick - no antibiotics or anything. Seems to be something they do. I finished up using pads of newspaper. it destroyed the carpet in that corner the end :(

If you can find a general area where she goes, puppy pads are great, and bicarb is wonderful. There is a spray you can get from pet stores to remove any smell - or Febreeze works just as well. Cleanig up is important - wee turns into nitric acid crystals when it dries - does wonders (not) for the furniture and floors.

Cuddles and scritches for your puss(es).