Help me with this rash

[Quiver0f10]

My 8 yo started having these red, raised bumps along his arms a few days ago. They are very itchy and he will have a line of them in a row. I did a google search and they look like fleas or *shudder* bed bugs? But then he started yesterday with a lacy red rash on his face, neck and arms and I thought fifths disease. But I have never seen fifths with raised red bumps. Also, he sleeps in a room with 3 of his brothers and none of them have any bumps or rash, which makes fleas or bed bugs unlikely ( I think). Oh another thing, we haven't travled, slept over night anywhere. Wouldn't we have had to pick up bb's somewhere? I mean you don't just "get " them. Sorry, I am
freaking here LOL

William who sleeps in there has had a fever for 2 days, which would fit with the fifths, but the 8 to has had no ferver or sickenss.

I am stumped. Any ideas?

[j.griff]

An allergy? I'd try an oatmeal bath, and wash his bed-clothes with baking soda in the wash and vinegar in the rinse and see if that helps. My ds will suddenly get odd rashes when he develops a sensitivity to laundry products, or something else he's been in contact with (and it itches like crazy).

[Quiver0f10]

I am using calamine and gave him benedryl, but I am flipping as to what's causing it.

[j.griff]

It is so aggravating trying to pinpoint the cause, hugs.