Itchy Urethra in 9 year old daughter

My daughter is 9 years old.  For about a month, she has been suffering with a severe itch in her urethra.  She has been to the doctor and they have tested her for bacteria and yeast.  They have also checked her urine.  She has no other symptoms.  No redness, rash or anything.  We have also tested for pinworms.  All of the obvious things have been looked at (soaps, laundry detergent, etc.)

Her next step is allergy testing.  I am hoping that someone can shed some light on a rare or unrelated cause for something like this.