You may have an abrasion or small skin tear on your labia. Urine flowing over the open wound maybe causing some discomfort. It may help to put some antibiotic ointment or Vaseline on it. These would provide a protective barrier.
If you have had unprotected sex or have had multiple partners in the past, there is the possibility of STD. Genitial herpes may cause sores.
Ultimately, if the discomfort continues, you need to be seen by your doctor.
14. February 2012
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