I, too, have recently found that even the slightest scratch, perhaps in response to a slight itch, becomes a welt and continues to itch until I calm it down with an "over the counter" hydrocortisone ointment. Since I know that I am sensitive to laundry detergent which hasn't rinsed out of my clothes, I have been double-rinsing anything that touches my torso. I am thinking that even a slight scratch in response to dry skin may leave the skin open to react to the allergin. Are you're welts mostly along the torso? Have you tried to see an allergist?