Black outs?

Is it healthy to black out, out of nowhere. No, I didn't have any drugs (that I know of) and I didn't drink beer (once again, that I know of).
I just got finished drinking my tea when suddenly I see/feel nothing. I think it went on for about 5 minutes. Apparently I was posting random stuff in an IM and googling lyrics to a song I've been thinking about for a while.
No, I don't think this was the first time, I think last night I blacked out for about 30 secs becuase one minute I found myself standing talking to my dad, the next minute I go "Woah" and appear laying down in a chair.
Also, when I got finished my second cup of tea, a part of my brain felt wierd, my neck cracked by itself (quietly), my head felt light... 30 seconds later my head feels very heavy and my vision changes 3 times, and then kind of gets blurred and there was a white outline in my eyes...
What is it? I don't know
Why is it? I don't know.
Also I'm pretty sure I'm drug free, I haven't smoked or anything like that...
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I copy and pasted this from the Furry Teens thread that I just made... So some info might be in it that you guys already know, they don't know me as well....

Maybe your body was too tired. Try getting some sleep.

Well... That might be it...
The Furry Teens admin said to goto the doctors and closed the thread ._.

dude this can be serious, tell do you have any family members who exhibit similar traits or a history of heart problems/blood clots? You should see a doctor 2 days ago!

I don't have any family members with those problems, at least not from blood.

this could still be quite serious, do you have any idea what a clot can do to you if it cuts off blood flow?

Kill me?