What Causes Itchy Testicles, Urethra Opening And Pain In Penis?

I am a mother of a 5 year old boy. He has been complaining of the shaft of his penis hurting as well as the urethra opening when he urinates. It is hard for him to pee into the toilet. The stream is steady but arches up. He has to push the shaft of his penis down for the stream to go into the toilet. The pain started mid April 2011. First he said his testicles were itchy, then the urethra opening, now it is the shaft. We have had urine tests and cultures performed by his pediatric doctor, which were negative. We also did baking soda baths for weeks in case it was ureathritis. We are scheduled to see a pediatric urologist July 19th. I am so concerned for my little boy. Please respond