Sherlock Who?

Let's just start out with the fact that detective work takes too much brain power for me. My poor son broke out in hives a couple of weekends ago, and I am stumped as to what could be the cause. I took him to the Dr. on Wednesday and had to sit through the grueling process of him getting blood drawn. *Tears* I think he is still mad at me. I didn't hear anything before the weekend hit and come Monday, I find out that the tests all came back negative for allergies. What?!? I thought it might be blueberries, but he's had those before with no reaction. That is the only thing that changed. I don't want to give him another rash/reaction so I am not sure if I want to really test my blueberry theory (even though the tests show he shouldn't react). My husband and I also think he could have found a nasty creature on the floor (i.e. a dead bug) and eaten that. He is getting around pretty good by now, and puts any and everything in his mouth. Usually bugs die in the house because of poison, right? I guess it makes sense if he ate a dead bug, he could have been reacting the insecticide or whatever else gross the creature was harboring. Please universe, give me an answer.... and tell me my son isn't eating bugs, Yuck.