I did a test on my arm after reading this article - Dermograhism - The Skin Writing Allergy because the more I read, the more I kept saying ah-ha, yep, oh my gosh! What I did to my arm in the photo above is draw a peace sign with the back of an eraser and I did not even push that hard. What you are seeing is about 3 minutes in - see the peace sign? By now it is a full-on whelp that is itching like hell! Have you ever had unexplained skin welts? Do you have a diagnosis of dermographism? Either way, make sure you check out the link...it is filled with tons of info and more resources...maybe even some answers for you!