What Causes 2 Missed Periods, Dizziness, Acne And Sore Nipples?

i have missed 2 periods, feel constantly sick and dizzy and have taken a pregnancy test every week for the last 4 weeks and it always comes back negetive. I also have a lot of discharge but have been cleard of any infections. Im alson breaking out in spots and i sometimes have very sharp almost searing pains in my nipples. im 19, what wrong with me?