Most cats do not behave as you describe just because they are getting older. Changed behavior is usually caused by a change in the cat's surroundings. Check for a new cat outside or perhaps someone moved in recently. Has your situation changed or have you recently changed the cat's food type? These types of changes can be very traumatic for a cat because all of the scents he/she is used to are no longer there. Think and observe your surroundings to see if you can find something that might cause this behavior. I had a cat once that changed how she behaved with me because the neighbor started to feed her outside while I fed her inside.