Side Effects Of Eating Finger Nails And Skin On Fingers

Hi, i just wanted to know if there are any serious medical issues that could got along with eating your own skin, or what if there is a term used for it? It consists of only eating finger nails, skin arround fingers, and skin from the bottom of ones feet. I know it's related to psychological isues, but i have been doing it since i was 7 and now i'm 20, and i still don't really understand what it is or how comon it is...