Umbilical hernia

Hey ladies

My son has an umbilical hernia. Doesn't seem to bother him at all, but today I've noticed that it seems to be sticking out a little more than usual, and it also has a kind of wet look to it. It sits under his nappy so perhaps some urine got on there- if that is probable, then how do I clean it? I've wiped it with a baby wipe and also wipe it gently at bath time but I don't want to hurt him by pressing on it too hard. Anyone ever experienced this? How soon did it go back to normal?

Thanks