Obsessed with smelling fingers and picking scalp...?

This is going to sound super weird, but I am trying to see if it is an honest problem. For as long as I can remember, I've had an obsession with smelling my fingers. I touch things and instantly smell my fingers. I also have an obsession with scratching my scalp, and collecting and smelling the dry skin. I love smelling my belly button, and the sweat under my breasts.. I lead an otherwise completely normal life. I'm about to graduate college, engaged, and my fiance doesn't care...but is this really an issue, or just a simple compulsion? Should I get help? It hasn't hurt me so far...