Something wrong with my son or not

I happened to find there\'s some discharge on my 10 years old son\'s underpant. This is going on for a few months. Sometimes, no discharge, sometime, a little bit. When I ask him if he feels any pain when he pees, he says No. His urine looks fine to me. He told me that he feels a little bit pain when he pulls his forskin on his pennis toward himself. Is there anything wrong with him?