Allergies are always a difficult problem to diagnose correctly. In general, there are a number of questions that your doctor
may ask you to determine if you have had any recent contact to some of the most common offending allergens.
One of the first questions that he or she may ask is if you have a history of allergies to anything else in the past. People tend to have allergies to the same or similar things, and so that can be a clue about what is going on currently. Also, your doctor will ask if there have been any changes to your routine, or if there is anything new that you have started coming into contact with.
The physical exam portion of your visit to your doctor will also be beneficial, as the distribution of the rash will indicate how you are coming into contact with the causative agent. For example, a rash on your hands and arms may stem from a new cleaning product that is being used on your desk at work or home. By reviewing your recent exposures and past history, your allergist can generally give you a good idea of what is causing the problem. Please speak to him or her.