idiopathic rash

In the good doc's own words, 'it means you're pathetic and I'm an idiot.' Took Canyon to the dr today early from school because he is covered on his stomach, chest and back with a red very itchy rash. I suffer the same, but in different areas from him. Doc doesn't know what it is; suggested it might be something we ate (unlikely) or wearing new clothes before they were washed (most likely). So, we are both on Benadryl and I have to switch to Dove and pick up a Rx for Canyon. He had it last year and so did I plus I just had it a month ago too. I'm thinking severe dry skin. Getting a humidifier too.