Itchy scalp=hair loss ??

My scalp itches,and when i slightly pull out a bunch of hairs on that area,a single or few hairs may fall out easly without any pain and that happens only on top of the head.I can feel and see thinning on front and a little bit on top of the head,while middle part is still strong.Its not receding but only thinning.What mkes it weird is that my father is not balding,his father has thick black hair,even my great grand fathers were not bald,only my both grandmas are quite bald and mothers father but not much.He is almost 80,and im 21.Whwt does the itch means?