A kid poked me with a thumbtack and I started bleeding a little? Am I going to get HIV? Please help me.

No, you're fine.

No, you're fine.

He did it to a bunch of other kids too.

Everyone is fine.

Everyone is fine.

Can you please explain how everyone is fine? I tend to over think and over react to these kinds of situations.

I tend to over think and over react to these kinds of situations
There's your answer.
The chances of infection in such a random manner are virtually ZERO.

That's not how HIV is spread.

What happens if he poked someone before and they started to bleed then he poked me?

Nothing. Nada. Zilch.

UNLESS one of the previous people that had blood drawen in this manner had HIV, there is NO chance of cross infection.
Even if one or more was infected the chances of any spread are also virtually ZERO.

Before this thread degenerates further it is now
http://mvny.org/images/closed.gif

But he could die from tetanus if the tack is rusty. ;)