What is this?

[Notnow]

Last week i somehow noticed i had thin spots on the top of my head. They were not visible from the sides, front or back.

[IMG]http://imgur.com/bgjEzaj[/IMG]
The day i noticed.

So, a day or two after, i decided to shave my head, because i believe that i should not "hide" it and i thought it won't look that bad.
I took some photos during the week.
Except the top of my head, the other parts, as i mentioned earlier, are fine.
I don't have receding hairline.

[IMG]http://imgur.com/5rFtSgV[/IMG]

Some are very disturbing to me, since it just appeared from nowhere.

[IMG]http://imgur.com/dzMSylj[/IMG]

Those four pictures were taken few hours ago:
[IMG]http://imgur.com/q7iUMa3[/IMG]

[IMG]http://imgur.com/O9LJjpl[/IMG]

[IMG]http://imgur.com/rIY6Uae[/IMG]

[IMG]http://imgur.com/7Hct2Bw[/IMG]
(behind it's fine)

I will be glad for some comments from experienced members.
Of course, i hope it's a temporal state, but i'm skeptic.

Thank you.