Sudden changes in cat

Question
My mother owns a 15 year old cat (saved from a wild litter - so I'm not sure the breed). In the past week or so Yoda has appeared to lose a lot of weight, her fur gets greasy though her skin in dry and she has dandruff. But what bothers me most is she's suddenly after all these years started urinating just outside of the litter box for no apparent reason, seems to have lost her appetite and drinks more than usual. We plan on taking her to the vet, but would like to know some of the possibilities of what we might be facing. Could you tell us what this might be and what kind of tests might need to be performed. Thank you!

Answer
Flakiness of the cat's skin usually has an internal cause, such as insufficient oils or fats in the diet.  Dandruff is common of inside cats because of no fresh air or it could be too much bathing, it could also be worms.  Your cat may have a Urinary problem and needs to see the vet about that.