Hi, I Have A 3 Year Old Who When He

Hi, I have a 3 year old who when he goes to urinate, cries in pain. He seems to hold it as long as he can and when you ask him what is wrong, he cries. He was taking to the doctor so often for this now I feel he doesn't say anything. At one time he would say it hurts but now he says he is ok. I was at his doctors this morning with him again I was informed if this continues they may circumcise him. My question is what does his foreskin have to do with him urinating?