21 year old female. How can I treat the bald spot near my neck? (Photo)

I've always had long thick hair... but recently found a spot in the back of my head that was completely bald. Neither of my parents have this problem and in there 60's. I saw my family doctor and he was convinced it was ring worm. So shampoo & ointment the whole nine... but there is NO ring on my scalp... and its gotten a lot worse. =\ its embarrassing..