Expectations with father? YOUR ADVICE PLEASE?

hello, my name hayashi. i am japanese student who study at american university. i been here 2 months. my father wishes me to be a doctor, however i feel that am better suited to paint. I do well in classes, but it does not please me to learn biology. How i tell father, i do not want to dishonor him but i wish to be painter. If i no be painter i don't know what to do. I am also concerned because i recently start drinking alcohol. I get in fights. How i straighten life out?