Help!

Let me just start off by saying I know this is kind of creepy, but we don't know what else to try!  I'm hoping that someone out there will have a good suggestion. 

Our oldest kid wakes up every day with a new bite; you know, like bed bugs.  They look like mosquito bites, or possibly spider bites, a small red bump.  He usually has one or two new ones a day, as many as eight, but they are spread out all over his body, not in one spot. 

We have washed and changed his sheets and everything on his bed, more than once, covered his mattress in plastic, etc. Finally, we took his whole room apart, washed the sheets, all the stuffed animals, took everything out from under his bed, off the shelves, vacuumed, removed anything suspicious (he has a rock collection and a bottle cap collection).  While we were dismantling his room, he slept in his brothers' room for two nights, and did not get any bites, so therefore, we deduce it is in his room.  We have never seen any bed bugs, spiders, anything that would bite him.  We looked up bites on the internet and found scabies, with numerous pictures; this is not what he has.  We have given him a mattress that was in the other boys' room.  This morning, he had a new bite on the back of his leg.  

No one else in the house gets bitten.  We have shampooed the carpets, we have thoroughly checked behind the furniture, under the furniture...  We do have pets; the cats sleep under his bed sometimes, but they sleep ON the beds of everyone else, including ours.  The dog doesn't really go in his room.  Does anyone have a suggestion??  Next call is to the pediatrician but you know, they have very limited hours and with H1N1 floating around, it's hard to get ahold of someone if you don't have the flu!  The only thing we have not tried is something chemical, like a bug bomb.  I guess we are down to this.  If anyone has a suggestion, we'd so appreciate it!