Suggest Treatment For Urticaria And Dustmite Sensitivity

i have an ongoing skin problem, I have seen many gp's and 2 specialists with no luck. ben diagnosed as insect bite, (biopsy) dustmite sensitivity, urticaria, possible cutaneous mastcytosis, food chemical intolerance, amongst others! antihistamines dont work much at all. they seem to for a week or so (like everything does!) but then don't work.