16 Years Feeling Weakness In The Hands, Difficulty In Holding Things, Discoloration Of The Fingers. Any Advice?

sir, my daughter aged 16 yrs student of 10th std . suffering from loss of strength of both hands from last 3 days.she finds difficult to even hold pen to write properly, unhole the buttons of dress, unable to tear chapati/bread to eat,blakish-brown fingers before nails ,she is unable to open hands completly thou there is no pain in hands so far. Her heigth 5 feet 5 inches, weight-55 kg, deit good,sleep good, very good in studies, but very senstive during exams. Main problem of hands fingers very low strenght to pick things..kindly advice....