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You are suffering from alopecia areata
. Alopecia areata commonly has well defined patches of hair loss. That is the localized variety. Suddenly hair growing white also is one of the signs of alopecia areata. Sometimes Alopecia areata can be diffuse if the activity of the disease is severe. You seem to be having a very active disease looking at the way it is shedding. It is advisable to see a dermatologist
at the earliest as you might require systemic steroids
to stop the activity along with topical treatments. Better not to delay as they can fall at an alarming rate. Relax, there is treatment , but do not delay.
Hope this helped