A person may be able to identify the cause of their rash based on the location of the rash or other symptoms they may experience. For example, swelling and breathing problems might indicate an allergy, while a fungal infection such as candidiasis can cause a rash in the skin folds. Factors such as whether the rash is flat or raised, peeling, or painful can help determine the type of rash. However, it is best to contact a doctor for an accurate diagnosis if a person develops a rash.