I have a sudden bald spot on my head and noticeable thinning of my hair at the scalp these past couple of days. I have no idea what would cause this; I haven't been stressed over the recent months, I haven't changed my diet, I don't tie my hair up ever, I haven't dyed my hair in months, and I don't straighten or curl my hair more than once a week including blow-drying it. Why is this happening? I am only 18!