white non itchy layer of dandruff

[thanxdoc]

i am 21 yr old boy, in the center-back of my scalp there are small non itchy white bumps, seems like layers of dandruff , when i harshly comb at tht part then a lot of dandruff gets created, i use zpto and ketoconazole shampoo but these non itchy bumps remain. when i use a fine toothed comb on the bumps then the bristles just seem to go around the bumps,if i put pressure then it leads to the generation of huge amount of dandruff as mentioned earlier,along with 2-3 mins itch and burn, the bumps are still their with some oil around it,besides i dont use oil or conditioner,neither any gel.if i just dry massage my scalp then i find fine hard thing just coming out of the skin(like small dandruff hard particles), sometimes my hair falls with a white thing at the bulb.kindly tell wht these bumps are and how can they go?