Vitamins

I work as a CNA. I work 12 hour shifts 3 days a week. On days I work I sleep from the time I get off (6 am) until 5 pm when I get ready for work. On other days I'll sleep for about 16-18 hours. I'm always tired and have a hard time waking up. My lip split open at the crack too and won't heal. I told all this to a nurse I work with and she said it sounded like vitamin deficiency. What are some ways I can help this? I already take the woman's one a day.