I used to get break through bleeding when I would start different brands of
the pill but not after being on the same one for a long time. Have you gained weight since you have been on it? Some pills loose potentcy if you are over certain weight to height ratio's. Which no one tells you unless you ask of course. You might want to call the doctor and see if you should change pills,
hormones change as we get older too, you may need more of one hormone and less of another now, and that could be causing the bleeding.