What Causes Rough White Patches On The Scalp?

This is for my wife:There are rough patches over the skull within the hair, the roots of which seem burdwened with white hard toothpate(resembles). When coumbed, white hard paste like residue gets out of the comb and some times the same are with hair roots and same is not dundrops.There is little itching tendence but the roots of hairs loosing smothness over the skull,getting inflated & uprooted resulting baldness over the concerned increasing patch during the time lapse. Local skin specialist advised to use/apply 1)Lomax T shampoo,2)Sternon-s lotion 3)ALCIZ-5 tab but after using the above three medicine for more than one & half months getting no improving result.Previously Gurnier hair colour naturals was in use but not now. Wanted remedial advice or address of good doctor either at Burdwan or at chinsurah or at chandannagore may be given for such treatment for ultimare cure.