You can ask your primary care doctor for a referral. If you live in the United States, you can search the American College of Allergy, Asthma, and Immunology list for a board-certified allergist. Sometimes the cause of your reaction will be obvious. If, for example, you ate a peanut and 10 minutes later your experienced anaphylaxis, there is a pretty clear culprit. If, however, you just went for a walk outside and experienced an allergic reaction, there are a multitude of allergens you may have encountered that triggered your attack. To help your allergist, write down everything you remember about the events leading to your reaction- what did you eat? Touch? Where were you? Did you take any medicine? These questions will all help your allergist determine the cause of your allergy. After talking with you and getting your history, the allergist will probably perform a skin test to determine what is causing your allergy. During a skin test, a drop of several potential allergens is placed on the skin, sometimes with a slight prick of the skin. After about 20 minutes, if you are allergic to a substance, a red, itchy bump will appear. This signifies to the allergist that this substance is causing your allergy, and he will treat you accordingly. Sometimes the allergist will also order an allergy blood test. This may be because you are on medication that could corrupt a skin test, you have a skin condition, or the allergist may just want confirmation of the allergy with another test. Blood tests are usually done in a lab and take several days to produce results. Even if your reaction was not severe, you should ask your allergist for a prescription for an EpiPen. Your symptoms may be worse the next time you have an attack, and having an EpiPen around could easily save your life.

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Write a summary of the previous text in Vietnamese:
Tìm bác sĩ chuyên khoa dị ứng tại địa phương. Ghi nhớ từng hoạt động khi bị phản ứng dị ứng. Xét nghiệm da. Xét nghiệm máu nếu cần thiết. Kê toa EpiPen.