About 3 months ago I went through the same thing with my 5 year old. Turns out my 5 year old had strep. Normally strep develops with a fever and sore throat (which my other daughter had). But apparently it can also develop as a rash-like thing that looks like bug bites. I thought she had the chicken pox due to little bite-looking things on her rear, arms, upper legs, torso, and hands. Very itchy. I took her to the pediatrician (had to go in the secret door so as not to expose other kids). Doctor said not chicken pox, must be some kind of bug bite. I washed all her sheets, vacuumed her mattress (even though it has a dust-mite cover), cleaned her carpets. She kept getting more. A few days later I took her back to the doctor when one of her glands in her throat was swollen and my littler one had a fever. The nurse ran a strep test and they both came back positive. Then the doctor looked at my 5 yo's rash again and said, "Oh yeah, that's strep." If my younger daughter hadn't developed strep the typical way, we'd probably still be trying to figure out what was up with my 5 yo so definitely mention strep to your ped. And good luck figuring out what it is.