What Causes Abnormal Periods, Increased Appetite And Sleep?

im sleepin loads and when im not asleep i am always tired. i am eatting loads and have never really eaten much. im always feel sick and get drunk really easy. this is not like me at all. my periods have all messed up there normally perfect every month and now i can come on 3-4 a month which can last from 1 day to a week. what could be wrong with me?