<<Disclaimer: Verify this information before applying it to your situation.>>

Your replies were helpful, as usual. I less helpless with feedback to work with. First, it would appear that increased sensitivity to gluten is common, after being gf for a while. Second, mottled skin over the entire body is not a typical gf symptom, although it may be an individual reaction. Those who responded that it was a possibility seem to suggest it may be an individual reaction to a foreign substance and themselves experience the following::
"My skin kind of glows red" as a warning prior manifesting symptoms of DH
" ingesting gluten for me causes the veins in my hands and lower arms  to puff out so much that they
literally looked like man veins after a huge work out".
"One of the ways I know when I have eaten gluten is that I experience an increased heart rate and I become very thirsty....". 
Other possibilities were just a virus, as happened to a person's non GF daughter. Strep was presented as another alternative, as was fifths disease (neither of the latter I think would fit with my son). Another person sent info that indicates 50% of the time it is from unknown origins, other times it is an arthritis reaction or associated with lupus. http://www.uklupus.co.uk/livedo.html .  Sigh........... Yes, the rash was identical to the picture, except my son looked even worse.  So now that I am more aware, I will present these varying possibilities to the GP, hoping of course, it was indeed just an anomaly. Thanks again.
Deb, Vancouver

*Support summarization of posts, reply to the SENDER not the CELIAC List*