There are a few things that it could be. If you're sexually active it could possibly be a sexually transmitted disease or sexually transmitted infection. Gonorrhea or Syphilis could cause discomfort and discharge, but is easily cured with anti-biotics and a possible shot from the doctor. Go see your doctor.
If it were only clear discharge, this would be normal. But the discomfort with the discharge could be an infection. You should get a urine test done, such as a urinalysis or urethral swab to test for common STDs. But you should definetly go see a doctor if this continues to be a problem.