my son has this rash on his face and he's had it for a couple weeks. It started on his chin and…

my son has this rash on his face and he's had it for a couple weeks. It started on his chin and every now and then it spreads to his cheeks and under his eyes... I don't know what it is or what to do to get rid of it and I'm a little worried... anyone have this issue and what did you do?