Just a couple things to add to the myriad posts by some of the best and most helpful people in the world.

That said I am also thinking could be renal issues and or diabetes.....We have three cats, would only eat dry food for years. One of our cats was suddenly drinking a lot and peeing a lot. The big giveaway was his breathe smelled ammonia like. turned out to be diabetic. As we do not want insulin in a cat, so we switched them to wet food. Worried our Maine coon wouldn't eat I told the wife no cat will starve itself...Now all three are happy and the diabetic cat is not even in triple digits when we test blood sugar.

Just my 2cnts
Pz
DS