Sudden hair loss on one side of head

A month ago I noticed some hair missing around my left temple. I'm fairly sure after a month it's worsened, and creeping backwards. It's appearing in a semi-circle pattern, but I emphasize ONLY on the left side of my head. It's a semi-circle from just to the left of the center of my forehead, to the temple area. When I pull my hair back this curve is very apparent. The hair located in that area that has not fallen out has been breaking and becoming very short. There is no type of hair loss on either side of my family tree, I haven't had any severe levels of stress, and I don't do anything to my hair (except wash it every few days with normal shampoo). Don't know if it's relevant, but I have premature graying hair as well, but my dad and aunt have that. Please help!