What test to ask for when diagnosed with dermographism

20 years ago I had a bladder surgery that went very wrong. I was septus, my ovary was abscessed flipped my bladder upside down. Internally hammer gain, three blood transfusions . Then I walked out of the hospital with mrsa. In the last 20 years, I've had 3 allergy test. all of them have been different. Also had 2 different dermatology allergy tests done both of those were different. I've had allergic reactions to things been tested for them, and they come back negative. I have seen every specialist and nobody knows what's wrong with me. Doctors tell me allergies, change all the time. I literally have a reaction to something every day, whether it be the Sun, my own sweat. Something I eat that I've eaten several times before. I brought up mass cell activation with the dermatologist.She's sending me back to the allergist because of the dermographism . What Test, do I ask for And from what specialty , the allergist ?