whts wrong with my red eared slider turtle?

  its october and really not to hot but def not cold and my turtle has stopped eating and ran under a rock and wont come out and wont eat last year it didnt hibernate so y this year and this early?? i have a filter pretty large tank with a good scenery whats wrong?
it doesnt matter if it isnt hibernating when the temp drops bellow normal then the feel a change in the season straight away. on of my yellow bellied sliders is doing the same. was the tank hotter last year??? i had mine in a closed top tank last year so the temp stayed pretty constant all year, but now they are in a much larger open top tank the temp is moer dependent on the air temp. if you room is colder than normal the turtle will start to calm down and be slower through the winter months. its normal its what happens in the wild. some people say that you should increase your water temp to combat this but it is natural and what your turtles should be doing anyway . keep feeding it as normal and dont force it. just make sure you dnt treat it any different to what you normal do and nature will do what it has to. good luck:)
It is simple reptile are cold blooded and in colder temps they slow down and stop eating it is most likely bruminating since most places don't get cold enough for RES to hibernate.
If you want your RES to remain active all year, you have to keep temperatures (air and water ) and day length stable throughout the year.