Talk to Dermatologist on Extreme Peeling Lips

i have problem related to my lips. they are continously peeling from the past 2 to 3 years. i have done all the things and once got checked up by dermatologist and she said that drink enough water and there is no other problem. i am drinking 10 to 13 glasses of water everyday but my lips are not getting better. they get dry and peeling both in summers and winters. i also mosturize them daily but i don't know what's the problem with tell me what can i do and what is the problem behind all of this