My 7 Year Old Son Has Very Irritated Skin Under

My 7 year old son has very irritated skin under his foreskin. He is circumcised. He can pull his foreskin back but there has been a small hole since he was very little that always has smegma coming out. He can hardly touch the area around the hole. I've taken him to a pediatric urologist when gets was 2, and they said that I needed to work on pulling his foreskin back more and the hole will open up and the problem will be gone. I tried, and it didn't work. This has just always caused him pain. I was able to get all the smegma I could out of the hole tonight while he was sleeping. It was too painful to do this when he was awake. I noticed that the hole looks like it is tunneling under his foreskin, and it definatley has way more smegma in it. He keeps himself clean, but he is so uncomfortable. And this hole has not gotten any better, yet worse in the past 5 years. What kind of doctor should I take him to to to further evaluate this?