many things can cause symptoms like this. even just exercising/sports can cause it. certainly I wouldn't be thinking cancer as a concern at his age!!
he certainly should be seen. Also encourage him to let his provider know that he is starting to be sexually active so that they can advise him on how to protect himself too. he should always be having protected sexual contact. We recommend if your pants are off, a condom should be on!!! also if he hasn't had his gardasil shots for hpv yet, now is the time for him to start the series.
grace