What Causes Sore Breasts After Withdrawal Bleeding While On Microgynon?

Hello, I have been on the contraceptive pill for 2 years (Microgynon) and have never had any problems / side effects. Every withdrawal bleed has always been on time. However, over the past few months, I have noticed that a few days before my withdrawal bleed is due to start, I have sore breasts. Is there a possibility that the pill is no longer working if I should be getting period symptoms like I had before I was on the pill?