Son, complaining of penis hurting while peeing, after swimming, no redness?

Possible bacteria and chlorine in water could cause this discomfort. Where you swim, indoor-outdoor, fresh or salt, all could harbor bacteria or agents that could cause problems. Know the area and if discomfort continues see your pediatrician.

If in a pool- a small amount of chlorinated water enters the urinary passageway it can do that- there can be other causes. If it persists have him checked out