What Causes Rash On Legs And Stomach?

My nephew has what looks like a rash on his legs and stomach, i have visited my doctor with him and 4 doctors had a look and could not diagnose it! they flare up when touched and go a reddish pink colour. i have tried e45 cream but it did not work. he has had this for a few weeks now but does not seem to cause him any discomfort.