My lips are always chapped ( I use chapsticks ) And it always happens to be my upper lips only. Any idea why?

Starting around when I was 13, my lips were always chapped. My diet isn't off, It's pretty normal I suppose. Someone said it was because I lack vitamin C so I started taking vitamin C pills. Didn't really do much. Anyways my lower lip is fine, but my upper lips are ALWAYS peeling/shedding. My friends say it pretty grimy. Any help would be awesome.