What Causes White Hair On Scalp Of Toddlers?

My baby s age is 3 years old. Her hair colour is black but last 2 days I saw 2-3 white hairs in scalp.Baby s weight is 14 kgs., So far no symtom of any allergy is seen but for last few days she was suffering from cold and cough and as per advise of doctor medicine Altime and nesal drops otrinoz was given to her. Please tell me the reasons and remidy, and also update me which oil, shampoo, food, vegetables and fruits can be given to her for white hair in scalp. I also used to give her Mustard oil ( Pure Mustard Oil) in her hair. Thanking you, Nabanita Choudhury