Im 15 and i realized i have a a strand of white hair.?

im 15 and i realized a piece of white hair growing on my head, what should i do? i hear sometimes you can get it because of malnutrition or stress, is that true? i haven't been eating breakfast for the past 2 weeks but i don't know how that could effect so fast. and im really really skinny. i don't dye my hair but i do straighten it. i don't know the reason and i wonder if its stress, but i usually cont stress maybe once or twice this week but that's all. my friends told me not to pull it and leave it there, they said it will fall off but what if i accidently comb my hair and it plucks off? will it spread??/how do i get rid of it??