You may be using facebook for quite a long time and liked many pages of your interest. Previously there were no system of verified pages on facebook, any page can be created by non official source therefore we can find multiple pages for the same interest. So the chances are you also liked fair bit of unofficial pages. After recent introduction of verified profile/page system, almost every firms and personalities verifying their facebook pages which can be identified with a blue tick sign.
So its time to unlike those unofficial pages you liked before and search for official pages of them. You can easily find your previously liked pages going to your profile>about tab. Happy facebooking! And dont foorget to say thanx for this tip 😉
Find more about facebook verified profile/page