Hi, Once this is clear that you have rash due to an allergic reaction which causes histamine intolerance as told to you by someone and that you are taking so many antihistamine the treatment can be formulated well. You are also loosing weight and the Surgeon told about steroid injection. I would advise you the following: As a dictum: anything under the sun including the sun can cause allergy hence it is your keen observation about hte foods, beverages and other factors like atmospheric changes, cloths, dust, mites, mildew, pollen around and all that you thin instigate or enhance your problems. Once identified avoid these at any cost and this prevention will help you the best for sure. Antihistamine help but sometimes if the allergy is severe oral steroids can be given in a tapering dosages so that you get well. You can go for skin allergy tests that may help in deciding the things to avoid. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, General Surgeon