Weird itchy raised bumps keep appearing on my body.

I keep getting strange almost mosquito like bumps on my body at night/when i go to bed/sometimes even relaxing in bed during the day time, but mostly at night.
I've ruled out the possibility of bed bugs because there are none in my apartment and the bites are completely different.
Here is a picture link of the bites that I keep getting.
http://i1204.photobucket.com/albums/bb420/Novajean/Snapshot_20111221_2.jpg
they aren't red or anything, my skin just raises up and begins to itch a lot for a few hours at most.
They tend to go away completely in a day.
I'm completely stumped. There are no bugs that I can see crawling on me or biting me. just the after effects.
I know it has something to do with my home as I don't get them when i go to other places.
I've sprayed for both bed bugs and cockroaches but this still keeps happening to me.
It is getting out of hand to the point where i'm having trouble sleeping in my own apartment. [i try to stay at friends houses as much as possible]
please tell me what I can do to help stop this once and for all!