What Causes Foreskin To Attach To Glans And Generate Pus In A Child?

hi, i havea 2 yr old boy, and he is not curcomsized, and his foreskin has become attatched to the head of his penis, that was a while back, more than a year ago, but now theres a pocket of what im assuming is puss, and the pressure from the pocket has made the foreskin let loose just enough to make a small hole to let the puss out, i have a appointment with a urologist, but i wanted an idea of whats going on and what the dr might recomend, thanks