I need help!

My 4 year old son recently developed some kind of bump at the base of his penis. It apparently is itchy, and seems to bother him. We’re taking him to the doctor tomorrow, but I was just wondering if anyone has had something like this happen to one of their kids? It’s not a sore, or a pimple. It’s a hard bump under the skin, I’m terrified it might be a hernia.