How Long Does The Withdrawal Symptoms Of Kelnor Last?

Due to insurance changes, I was forced to switch from zovia to kelnor. After a few months on kelnor, I had acne and migraine flair ups. I took the zovia continuously (no placebos) to control the migraines. I was able to switch back to zovia after some on-line research indicated kelnor could be causing my problems. After years on zovia with absolutely no issues, how long before the symptoms that appeared with the kelnor go away and things return to normal?