My Baby Has a Strange Rash...(??)

I posted this question on the infant care forum, but thought you guys might have a little more insight. I have a one year old girl who presented with a goosebump-looking rash on tuesday morning. It is all over her body with the exception of the lower portions of her legs and arms, feet and hands. Her face gets red, blotchy looking marks when the sun is on it for any length of time. She has had no other symptoms except this morning she's starting to itch. Took her to a nighttime doc wednesday night who could only surmise that it was a virus, or something she came into contact with (like the new sleeper she wore to bed monday night.) I don't think it's a virus because I believe her twin sister would have gotten it by now. I have changed and washed her sheets, washed all of her pajamas in dreft, am dressing her only in cotton materials, tried hydracortisone topical cream, steven's cream, aquaphor, eucerin, benadryl. This rash has not changed or diminished at all. Does anyone have any idea what this could be? What could be causing it? When it might go away??? What I can do??? Please, any advice or suggestions would be greatly appreciated. Thank you.