Hello! My Son Is 6 Years Old And Has This

Hello! My son is 6 years old and has this problem that really bothers him. He is always complaining that his "penis is pinching". I had his pediatrician examine him and said he is fine in that area but I know to well that something isn't right. I had him point exactly where it is pinching and he points to the tip of his penis where the whole is. Not red, not infected and nothing there that I can see. Concerned there might be something going on inside!?